Establishment by Chalicea

The wordplay in each across clue yields an extra letter in addition to those required by the solution. Read in clue order, these will help solvers complete the perimeter, appropriately surrounding the unclued 17 down.

    8    Deer encircling goose, a basic assumption (6)
    9    Universal truth; return of feudal tax involves damage (6)
    10    Sweetened water for baptism of friend - incomplete ceremonial observance (5)
    13    Great rigour intermittently producing Italian sauce (4)
    14    Nice smart set, maybe, mounted clumsily after instrument lost power (9, 2 words)
    17    Question US about processed core in tree genus (7)
    18    Letters in a frenzy, short of time (3)
    19    Foolish rambling detour including outskirts of Iona (7)
    20    Untruths; wicked recalled final parts of ones (4)
    21    Be of one mind, in Braemar, about gutted babbler fowl (5)
    23    Lambert must be dropped from team in fact (4)
    25    Pointed sticks holding up mechanical devices for reducing slack, (4-3)
    27    Hogshead, a contemptible thing (3)
    28    Old warhorse's cover, robust strips of malleable metal (3-4)
    29    Huge bird, headless hen wandering in Scottish city (9)
    32    Plant junglis trimmed (4)
    34    Maybe a nicer person born on April 1st, for example (5)
    35    This felt hat gives surprising liberty (6)
    36    Peculiar feature of dialect of small sibling in US college hostel (6)
    1    Surprise expressed with American soldiers chasing dogs (6)
    2    For the given reason inordinately anti extremes of harassment (6, 2 words)
    3    Not, for example, a reptile following Nile's limits (7)
    4    Bent structure evident primarily in African antelope (4)
    5    Contempt expressed when weaver bird is decapitated (3)
    6    Fix cost of entertaining northern nobleman (6)
    7    Among well-informed English in revolt, the French Marat, for example (11, 3 words)
    9    Marriage portion; very small amount (3)
    11    Amoral quid accepted dubiously in assembly plant (11)
    12    Most bloody and most shabby in Glasgow, good for a bit of overhaul (7)
    15    Greek sorceress cut short old Persian inhabitant (4)
    16    Troublesome git sent out (7)
    21    Boast about dress (4)
    22    Grow beans for a start and force in a chosen direction (7)
    24    Judge of personal magnetism within revolutionary ring, the French being absent (6)
    26    Expression of disgust with melody mostly in variety of eastern languages (6)
    27    Mass prejudice related to senescence in ancient priestly teaching (6)
    30    Part of cliquey Ozzie's casual change of direction (3)
    31    Trimmed reddish fish (4)
    33    Nigerian charm backfires! (3)
To enter this competition, send your entry as an image or in list format (including the perimeter), to before the 8th July 2013. The first correct entry drawn from the hat will receive a copy of one of the range of books which has been donated by Chambers.