Paint left large streak (7)
I believe the answer is:
portray
'paint' is the definition.
(I've seen this before)
'left large streak' is the wordplay.
'left' becomes 'port' (left side of a ship - opposite of starboard).
'large streak' becomes 'ray' (ray can mean a streak or beam).
'port'+'ray'='PORTRAY'
(Other definitions for portray that I've seen before include "Describe in words or make a picture" , "Depict in art" , "sketch" , "Delineate" , "Depict, present" .)