Sea dog to talk foolishly about current (6)
I believe the answer is:
pirate
'sea dog' is the definition.
(thesaurus)
'talk foolishly about current' is the wordplay.
'talk foolishly' becomes 'prate' (I've seen this before).
'about' indicates putting letters inside.
'current' becomes 'i' (symbol for electric current).
'prate' enclosing 'i' is 'PIRATE'.
'to' acts as a link.
(Other definitions for pirate that I've seen before include "Hook", for example" , "Use (another's work) for profit without permission" , "Copyright infringer" , "One who infringes another's copyright" , "Sea-robber" .)