Not much spare? (6)
I believe the answer is:
slight
I believe this clue is a double definition.
'not much' is the first definition.
(similar in meaning)
'spare?' is the second definition.
(thesaurus)
(Other definitions for slight that I've seen before include "Slim or tenuous" , "Small, snub" , "Deliberate discourteous act" , "Put down" , "cut" .)