Shell out for peas, etc. (3)
I believe the answer is:
pod
'shell' is the definition.
(synonyms)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for pod that I've seen before include "Seed container" , "Elongated seed case" , "Marine school" , "A seedcase; some whales" , "Hull" .)