Such a comic not suitable for sitcom? (5,2)
I believe the answer is:
stand-up
'such a comic' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
(Other definitions for stand-up that I've seen before include "Type of comedian" , "Performed solo (of a comedy routine)" , "Form of comedy" , "Sort of comic (to be counted?)" .)