Row under circle in colour (6)
I believe the answer is:
orange
'colour' is the definition.
(I know that orange is a type of chromatic color)
'row under circle' is the wordplay.
'row' becomes 'range' (range can mean a row or chain of things).
'under' means one lot of letters go next to another (in a down clue, some letters go below others).
'circle' becomes 'O' (O is a circle).
'range' after 'o' is 'ORANGE'.
'in' acts as a link.
(Other definitions for orange that I've seen before include "Type of fruit from which bergamot comes" , "Dutch royal house" , "An ogre (anag.)" , "Unrhymable word?" , "Order of the North" .)