Gorilla in travelling funfair (7)
I believe the answer is:
ruffian
'gorilla' is the definition.
(thesaurus)
'travelling funfair' is the wordplay.
'travelling' is an anagram indicator.
'funfair' anagrammed gives 'RUFFIAN'.
'in' is the link.
(Other definitions for ruffian that I've seen before include "Yobbo" , "Roughneck" , "Violent criminal" , "Funfair (anag)" , "Scoundrel" .)