Many barrels among this smuggler's contraband? (3-6)
I believe the answer is:
gun-runner
'many barrels among this smuggler's contraband?' is the definition.
'gun-runner' can be an answer for 'smuggler's' (gun-runner is a kind of smuggler). I'm not certain of the remainder of the definition.
'many barrels among this smuggler's' is the wordplay.
'many barrels' becomes 'gun' ('gun barrel' can be a synonym of 'barrel'. I am not sure about the 'many' bit.).
'among' is a charade indicator (letters next to each other).
'this smuggler' becomes 'runner' (synonyms).
'gun'+'runner'='GUN-RUNNER'
Can you help me to learn more?
(Another definition for gun-runner that I've seen is " Arms smuggler".)