Bill feeding duck and lark (8)
I believe the answer is:
escapade
'lark' is the definition.
(both can mean an adventure or amusement)
'bill feeding duck' is the wordplay.
'bill' becomes 'ad' (advertisement stuck on wall).
'feeding' is an insertion indicator (one word is fed by another set of letters).
'duck' becomes 'escape' (I've seen this before).
'ad' going into 'escape' is 'ESCAPADE'.
'and' is the link.
(Other definitions for escapade that I've seen before include "Madcap adventure" , "Wild and exciting undertakings" , "Daring stunt" , "Caper" , "Mischievous exploit" .)