Add to general unravelling (7)
I believe the answer is:
enlarge
'add to' is the definition.
(thesaurus)
'general unravelling' is the wordplay.
'unravelling' indicates an anagram.
'general' is an anagram of 'ENLARGE'.
(Other definitions for enlarge that I've seen before include "Gleaner (anag.)" , "go into greater detail" , "Make bigger in general" , "Describe in more detail" , "General (anag)" .)