Full theatre -- allow encore at the end (7)
I believe the answer is:
replete
'full' is the definition.
('replete' can be a synonym of 'full')
'theatre allow encore at the end' is the wordplay.
'theatre' becomes 'rep' (I've seen this in other clues).
'allow' becomes 'let' ('let' can be a synonym of 'allow').
'at the end' suggests the final letters.
The last letter of 'encore' is 'e'.
'rep'+'let'+'e'='REPLETE'
(Other definitions for replete that I've seen before include "Filled, sated" , "charged" , "Filled, well supplied" , "Chock-a-block" , "Completely filled" .)