Left back extremely heavy prize (6)
I believe the answer is:
trophy
'prize' is the definition.
(I know that trophy is a type of laurels)
'left back extremely heavy' is the wordplay.
'left' becomes 'port' (left side of a ship - opposite of starboard).
'back' says the letters should be written in reverse.
'extremely' suggests removing the centre (only the extremes of the word are used).
'heavy' with its middle removed is 'hy'.
'port' reversed gives 'trop'.
'trop'+'hy'='TROPHY'
(Other definitions for trophy that I've seen before include "Object symbolising success" , "Cup given as prize for victory" , "Winner's prize" , "Cup, say, awarded as a prize for victory or success" , "leading award" .)