One who longs to eat crab's head or claw (6)
I believe the answer is:
pincer
'claw' is the definition.
(synonyms)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for pincer that I've seen before include "Surrounding (movement)" , "Claw, nipper" , "This movement is a converging attack" , "Lobster's claw" , "Front claw" .)