Clutch starts to eat small crabs (6)
I believe the answer is:
gripes
'crabs' is the definition.
(crab can mean to gripe or complain)
'clutch starts to eat small' is the wordplay.
'clutch' becomes 'grip' (synonyms).
'starts to eat' becomes 'e' (I can't justify this - if you can you should give a lot more credence to this answer).
'small' becomes 's' (abbreviation - e.g. clothes size).
'grip'+'e'+'s'='GRIPES'
(Other definitions for gripes that I've seen before include "Grouses, beefs" , "Complaints" .)