Bill wandering into Aldi further (10)
I believe the answer is:
additional
'further' is the definition.
(synonyms)
'bill wandering into aldi' is the wordplay.
'bill' becomes 'ad' (advertisement stuck on wall).
'wandering' indicates anagramming the letters.
'into'+'aldi'='intoaldi'
'intoaldi' is an anagram of 'ditional'.
'ad'+'ditional'='ADDITIONAL'
(Other definitions for additional that I've seen before include "with sums, perhaps" , "Extra" .)