Metal grating (6)
I believe the answer is:
grille
'metal grating' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for grille that I've seen before include "Protective lattice" , "Part of an air-cooling system" , "Protective metal framework" , "Frame of bars" , "A metal grating in door or window" .)