Rogue caught accomplice dividing plunder (9)
I believe the answer is:
scallywag
'rogue' is the definition.
(I know that rogue can be written as scallywag)
'caught accomplice dividing plunder' is the wordplay.
'caught accomplice' becomes 'cally' (I can't justify this - if you can you should give a lot more credence to this answer).
'dividing' is an insertion indicator (inserted letters divide the word).
'plunder' becomes 'swag' (synonyms).
'cally' put inside 'swag' is 'SCALLYWAG'.
Can you help me to learn more?
(Other definitions for scallywag that I've seen before include "Good-for-nothing - undersized animal" , "Delinquent" , "Rogue" , "A slangy rascal" , "reprobate" .)