Group deny act is rubbish (9)
I believe the answer is:
syndicate
'group' is the definition.
(syndicate is a kind of group)
'deny act is rubbish' is the wordplay.
'rubbish' indicates an anagram.
'deny'+'act'+'is'='denyactis'
'denyactis' anagrammed gives 'SYNDICATE'.
(Other definitions for syndicate that I've seen before include "Association of people or firms for business purposes" , "We might enter lottery" , "Publish simultaneously in a number of newspapers" , "Affiliated group" , "Group working together to promote common interest" .)