Not I by Ozzie

From the definer of a number of clues one letter has been removed. (All possibilities should be considered; first thoughts may not be helpful. The clue may not make sense when the letter is replaced.) Taken in clue order, the missing letters yield a thematic phrase. All other clues are normal: each leads to a word or words that, before entry, must be mutilated once (sixteen offer a real choice) in a way suggested by the phrase; the resulting light is usually a non-word. In asterisked clues the mutilation, though straightforward, is in more than one part. The unclued lights (one singularly stressed), considered as a group, are also governed by the phrase. The authority is Chambers, but the meaning of one singular is given for the plural only, and the common conjunction of words at 31 is, unsurprisingly, not given, though the mutilated form is. Other exceptions (next six in OED): 17 (& Webster, etc), 39, 41 Dn, and the spelling at 8 and at 46; the derived form at 18 Ac (& Macquarie, etc); one French word; one Latin; one Italian. Punctuation may mislead. And now - begin!

Across
3 (2 words) More than one tree trunk placed on trestle for sawing butts
10 Conservative top-class plastic surgery performed on ocular gives ... ocular!
11 After a long time user's thrown scrapings away
13 To lie top underneath indeed is to be prone
*14 No heavy metal? I'll take charge if hot singing lead and record company need a band-leader
16 Sent by flier to China - fabulous, the East
21 Hoist petard - no cess - essentially inferior
22 Put in order, put in order
24 Playing soccer with an element of a degree, a very small one
27 Like, ay, one from environs of York, this? Possibly
29 See Toad, say, drive extremely hard, having a bit of an accident before overturning
34 Hastily arrange score at cricket practice or a dressing game
35 Airmen are returning from a distance
36 See one of Beecham's little things given in reaction: a short work by, e g, Tchaikowsky
37 Train-driver's assistants take time for temporary diversion at work
41 To live the part is to lose '1'
*43 Flat needs coin for restoration; such a flat needs nothing more
48 Tibetan male - cross, popular - after a better place in-house, becomes a sort of GM
49 Top of spacecraft - other end dropped in and exploded in a moment
50 (2 words) Pisan truce: when the last's surrendered, wreath can be arranged
Down
1 Dwelling on River where rafter stays
2 Finally, resistance fighting that's not so bold
3 Hut needs internal support for housing of trooper
4 Drum roll - dance
5 Injure adult entering women's quarters
6 'Grease': a M. English entry?
7 Odds and ends, particularly of art or vertu [sic] objets?
8 Nuclei of negative charges are spent, leaving dead connecting parts
9 Eastern Stoic yields, cutting ancient Roman
12 Pack treasure for auditor
I5 Second last's out - American's healthy condition
17 The first of the U .S. witnesses become their surrogate plaintiffs
18 Sounds hoarse - back track
19 The sound of hookers leaving the front rows
20 'Dry' old Tory PM, unfulfilled, is to leave party
23 Right palm holding ring is grotesque
26 Here's a gee-gee with a Mounted Policeman: he'll charge fIrst
28 An actor's right to appear in male lead of Sexual Desires
30 Rousing bells: after first two have gone off see more than one wake Robin
31 (2 words) It may be found in a lot of bombs: watch rotating part with unceasing caution
32 Skunk's coat is ruffled
33 My destiny: to be placed under a governor
34 Different, contrary, unlimited, dry
36 Yarn explaining elision in French article
38 Women's very small clothing needed for maid
40 Takes some food in Escoffier?
41 Very large network without returns is no longer to broadcast
42 Assistants rise, giving seat to Madonna
44 Notes uttered in old madrigal
45 Rock guitar left jumping turn - very cool!
47 Dodo's not even part camel

To enter the competition send your solution in list format plus a cryptic clue to the thematic phrase to derek@crosswordcentre.fsnet.co.uk before 1st September 2002. The writer of the best clue will receive a copy of Chambers Back-Words which has been donated by the publishers. If you wish to express your opinions on this puzzle you may contact the setter at tjoclarke@hotmail.com