Left pig covered in pig fat (8)
I believe the answer is:
larboard
'left' is the definition.
(synonyms)
'pig covered in pig fat' is the wordplay.
'pig' becomes 'boar' (male pig).
'covered in' means one lot of letters goes inside another.
'pig fat' becomes 'lard' (I've seen this before).
'boar' placed inside 'lard' is 'LARBOARD'.
(Other definitions for larboard that I've seen before include "Port (nautical)" , "Left side of ship" , "left at sea" , "Side of ship for Labrador" , "Port; labrador (anag.)" .)