Cross, as one scuttling off? (6)
I believe the answer is:
crabby
'cross' is the definition.
(synonyms)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for crabby that I've seen before include "Bad-tempered, irritable" , "In bad temper" , "Cantankerous like crustacean" , "Ill-tempered" , "Bad-tempered like common crustacean" .)