I sat shocked, receiving bill for sports grounds (6)
I believe the answer is:
stadia
'sports grounds' is the definition.
(I've seen this before)
'i sat shocked receiving bill' is the wordplay.
'shocked' indicates an anagram.
'receiving' is an insertion indicator.
'bill' becomes 'ad' (advertisement stuck on wall).
'i'+'sat'='isat'
'isat' anagrammed gives 'stia'.
'stia' enclosing 'ad' is 'STADIA'.
'for' is the link.
(Other definitions for stadia that I've seen before include "Sports grounds" , "Large sports venues" , "major venues" , "Bowls" , "Big venues" .)