Scallywag, one providing seafood (6)
I believe the answer is:
scampi
'seafood' is the definition.
(I've seen this before)
'scallywag one' is the wordplay.
'scallywag' becomes 'scamp' ('scamp' can be a synonym of 'scallywag').
'one' becomes 'i' (Roman numeral).
'scamp'+'i'='SCAMPI'
'providing' acts as a link.
(Other definitions for scampi that I've seen before include "Crumby seafood dish" , "Cooked Norway lobster" , "Fried seafood" , "Prawns (fried with breadcrumbs)" , "Cooked Norway lobsters" .)