Refracting object (5)
I believe the answer is:
prism
'refracting object' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for prism that I've seen before include "Female character in The Importance of Being Ernest -- optical device" , "Crystal form" , "Refracting body" , "Optical device used to invert an image" , "Optical device used to deviate a beam" .)