Chewed, green rind - a watermelon rind? (5)
I believe the answer is:
gnawn
'chewed' is the definition.
Although both the answer and definition are past participle verbs, I don't see how they can define each other.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for gnawn that I've seen before include "Nibbled at" , "Bit in rage" , "worried persistently" .)