Bill accepts armed conflict prize (5)
I believe the answer is:
award
'prize' is the definition.
(I know that prize can be written as award)
'bill accepts armed conflict' is the wordplay.
'bill' becomes 'ad' (advertisement stuck on wall).
'accepts' means one lot of letters goes inside another.
'armed conflict' becomes 'war' (I've seen this in another clue).
'ad' placed around 'war' is 'AWARD'.
(Other definitions for award that I've seen before include "medal, perhaps" , "certificate?" , "Give, as an honour" , "Trophy or medal, for example" , "Prize -- gift" .)