Possibly draw flatfish to east of harbour (7)
I believe the answer is:
portray
'possibly draw' is the definition.
(drawing is a type of portrayal)
'flatfish to east of harbour' is the wordplay.
'flatfish' becomes 'ray' (I've seen this before).
'to east of' means one lot of letters go next to another (some letters go to the right of others).
'harbour' becomes 'port' (I've seen this before).
'ray' after 'port' is 'PORTRAY'.
(Other definitions for portray that I've seen before include "Use words to describe" , "Describe in words or make a picture" , "Depict in art" , "Depict, present" , "Delineate" .)