Ringleader crept in to smuggle pot (3)
I believe the answer is:
urn
'pot' is the definition.
(I know that urn is a type of pot)
'ringleader crept in to smuggle' is the wordplay.
'ringleader' becomes 'r' (first letter of ring).
'crept in' becomes 'un' (I can't explain this - if you can you should believe this answer much more).
'to smuggle' indicates putting letters inside (smuggle can mean to secretly carry).
'r' inserted inside 'un' is 'URN'.
Can you help me to learn more?
(Other definitions for urn that I've seen before include "Large vessel, for tea perhaps" , "A ceremonial vase as for human ashes" , "One carrying coffee or tea" , "Tall stemmed vase" , "A large vase, perhaps for holding ashes" .)