Lark's short bill seen in flight (8)
I believe the answer is:
escapade
'lark's' is the definition.
(both can mean an adventure or amusement)
'bill seen in flight' is the wordplay.
'bill' becomes 'ad' (advertisement stuck on wall).
'seen in' is an insertion indicator.
'flight' becomes 'escape' (flight can mean an escape).
'ad' inserted into 'escape' is 'ESCAPADE'.
'short' is the link.
(Other definitions for escapade that I've seen before include "A reckless or mischievous adventure" , "Piece of reckless mischief" , "Wild adventure" , "Caper" , "Daring adventure" .)