Invoice committee for hoarding (9)
I believe the answer is:
billboard
'for hoarding' is the definition.
(synonyms)
'invoice committee' is the wordplay.
'invoice' becomes 'bill' (synonyms).
'committee' becomes 'board' (board is a kind of committee).
'bill'+'board'='BILLBOARD'
(Other definitions for billboard that I've seen before include "Advertising hoarding" , "advertising space" , "American hoarding" .)