Paint a picture of harbour and fish (7)
I believe the answer is:
portray
'paint a picture' is the definition.
(I've seen this before)
'harbour and fish' is the wordplay.
'harbour' becomes 'port' (I've seen this before).
'and' says to put letters next to each other.
'fish' becomes 'ray' (ray is a kind of fish).
'port'+'ray'='PORTRAY'
'of' acts as a link.
(Other definitions for portray that I've seen before include "sketch" , "Show" , "Delineate" , "Play" , "Depict, present" .)