Talk too much about one buccaneer (6)
I believe the answer is:
pirate
'buccaneer' is the definition.
(a buccaneer is a pirate)
'talk too much about one' is the wordplay.
'talk too much' becomes 'prate' (I've seen this in another clue).
'about' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'prate' placed around 'i' is 'PIRATE'.
(Other definitions for pirate that I've seen before include "fake" , "Corsair" , "Rat pie (anag)" , "Illegally-copied (version)" , "Seaborne robber" .)