Draw fish in study (6)
I believe the answer is:
crayon
'draw' is the definition.
(crayoning is a kind of drawing)
'fish in study' is the wordplay.
'fish' becomes 'ray' (ray is a kind of fish).
'in' indicates putting letters inside.
'study' becomes 'con' (I've seen this before).
'ray' inserted inside 'con' is 'CRAYON'.
(Other definitions for crayon that I've seen before include "Colouring pencil" , "Drawing-stick" , "Child's colouring stick" , "One colours with this" , "Drawing implement" .)