Theatre character in shape (6)
I believe the answer is:
repair
'shape' is the definition.
(thesaurus)
'theatre character' is the wordplay.
'theatre' becomes 'rep' (I've seen this before).
'character' becomes 'air' (air can mean a character or mood).
'rep'+'air'='REPAIR'
'in' is the link.
(Other definitions for repair that I've seen before include "Make good again" , "resort" , "remedy" , "retire" , "Proceed - restore" .)