Husband Bill feeds pigs and dogs (7)
I believe the answer is:
shadows
'dogs' is the definition.
(dog can mean to follow or shadow)
'husband bill feeds pigs' is the wordplay.
'husband' becomes 'h'.
'bill' becomes 'ad' (advertisement stuck on wall).
'feeds' is an insertion indicator.
'pigs' becomes 'sows' (I've seen this before).
'h'+'ad'='had'
'had' going inside 'sows' is 'SHADOWS'.
'and' acts as a link.
(Other definitions for shadows that I've seen before include "They're cast by blocking the sun" , "Dark things" , "1960s band" , "Follows" , "Dogs" .)