4055 fiDlEDE by Waterloo

This was a fairly straightforward puzzle from Waterloo. The preamble explained everything. “Letters or groups of letters repeated consecutively, must be entered once only, in capitals, and other letters must be entered in lower case.” This explained the title, fiddle-de-dee, in the format of the puzzle. A grid with no symmetry allowed a wide selection of repetitions.

Across
1 Pointless infant follows to serve small pieces of meat with vegetables (3)
KABAB KA (serve) + BAB(e)
3 Old record starts to revolve and engages arm, perhaps (6)
 REMEMBER R(evolve) + E(ngages) + MEMBER
11 Hurrah! Not one ingredient in violet perfume (4)
IONONE IO (hurrah) + NONE
12 What's needed is modulated quiet reprise (10)
PREREQUISITE Anagram QUIET REPRISE
13 Skinned fruit, as they used to say - I don't get it (2)
ANAN (b)ANAN(a)
15 Unexpected measureless obstruction encountered particularly in the White Nile (3)
SUDD SUDDEN less EN (a measure!)
16 Shut out, not do as well (2)
TOO TO (shut) + O(UT) less UT (the note DO)
17 Cheers rubbish Australian (2)
TATA TAT + A (Australian)
18 Drink produced from exotic tobacco - consumption intermittently dropping (3)
COCOA Anagram TOBACCO less TB (consumption)
20 Just about satisfactory repeated note (2)
SO-SO SO repeated
21 Worsted backing initiator of surprising departure (5)
EGRESS SERGE reversed + S(urprising)
22 A dealer in killing cheek, in, for instance, Indiana (5)
ASSASSIN SASS (cheek) in AS IN (Indiana)
23 Tinker returning indignant response to "You didn't" to Central Office of Information (5)
DIDICOI DID I?!  + COI (Central Office of Information)
25 Blend of a titter and a teehee I hear naughtily leaving sofa (5)
TÊTE-À-TÊTE Anagram A TITTER A TEEHEE less anagram I HEAR
27 Black one favours some of our relations (6)
BABOONS B (black) + A + BOONS
29 The Duke noting wrongly omitted measure (2)
ELL ELLINGTON (the Duke) less anagram NOTING
30 Game in which tailless dart is thrown back to last of team (4)
MORRA ARRO(w) reversed + (tea)M
34 Announce politician backing left (3)
BILL L (left) + LIB reversed
35 Flower essence mixed in gangland, slyly dropping drug from the east (5)
YLANG-YLANG Anagram GANGLAND SLYLY less LSD (reversed)
36 Not quite what's wanted before wedding (2)
NEE NEE(d)
37 Rank good mood high for monitor (10, two words)
KOMODO DRAGON Anagram RANK GOOD MOOD
40 Votes against including old rule about bale wrapped in hide (5)
SEROON O (old) + R (rule) in NOES reversed
41 Disdaining the improper material with crazy ending (5)
 STUFFY STUFF + (craz)Y
 
Down
1 Tend to look back (3)
KEEP PEEK reversed
2 Books about the old affirmative answer, sleep (4)
BYE-BYES YE (old form of THE) in BB + YES
3 Relax about research work, where you raise your hand for attention (9, two words)
REQUEST STOP QUEST in REST + OP (work)
4 Potential hacker without general intelligence - I'm scared (2)
EEK GEEK less G (general intelligence)
5 Improvement is in footwear (4)
BOOST ‘S in BOOT
6 Central part of cock removed, resulting in noisy fan (5)
ROOTER ROO(s)TER lacking central letter
7 Number caught in source of lava gets back, a diminutive god has favoured me (5)
ANNETTE TEN in ETNA all reversed
8 Happened on a saint, a gal in transformation (7)
METASTASIS MET (happened) + A ST + A SIS (a gal)
9 Source of varnish before painter gets dry in the middle (2)
ARAR A (before) + RA (painter) + (d)R(y)
10 Hiawatha's grandmother drops end of stick and turns up wind (5)
SIMOON NO(K)OMIS reversed
14 Second to the finish in midday non-event (2)
NO-NO NOON with 2nd letter moved to the end
18 Half cook heart of Scots tenderloin employing initially fireproof dish (4)
COCOTTE CO(ok) + s(COT)s + initial letters Tenderloin Employing
19 Indian leaves when Lapp loses one (4)
ASSAM AS (when) SA(a)M
21 Old book from unconfirmed date (3)
EDDA Hidden
24 New start anyhow from cotoneaster, and here I am (3)
COOEE Anagram COTONEASTER less anagram N (new) START
26 Fishy slaughter reversed in early English tale's end (5)
EEL-LIKE KILL reversed in EE + (tal)E
27 Dance, dance half feet off (3)
BALL BALLET less (fe)ET
28 Apparently singular announcement of marriage in district on the borders of Hungary (5)
BANNAT BANN (!) + AT
31 Warriors from the east release divided Burundi from hell (4)
TATARS TA(r)TAR(u)S less RU (Burundi)
32 Depart after batting stroke (4)
IN-OFF IN (batting) + OFF (depart)
33 Maid drops first sausage (4)
WEENY (t)WEENY
34 Master heard in fold? (3)
BAAS 2 definitions Ref sheep-fold!
35 Two lads return, dropping their books. This is expected to come up again and again (2)
YOYO BOY BOY reversed less BB (books)
38 Low state of mind with no hint of dementia (2)
MOO MOOD less D(ementia)
39 Blow all movement (2)
DADA DAD (blow) + A (all)