Talk about current lawbreaker at sea (6)
I believe the answer is:
pirate
'lawbreaker at sea' is the definition.
(criminal operating at sea)
'talk about current' is the wordplay.
'talk' becomes 'prate' (to prate is to talk nonsense).
'about' is an insertion indicator.
'current' becomes 'I' (symbol for electric current).
'prate' placed around 'i' is 'PIRATE'.
(Other definitions for pirate that I've seen before include "Silver, perhaps" , "Illegal" , "One who infringes another's copyright" , "plagiarist" , "Penzance marauder ?" .)