Irritating drain cover (7)
I believe the answer is:
grating
I believe this is a double definition.
'irritating' is the first definition.
(grating is a kind of irritating)
'drain cover' is the second definition.
(a drain may be covered by a metal grating)
(Other definitions for grating that I've seen before include "Frame of iron bars to block passage but allow air" , "Harsh sounding" , "Unpleasantly harsh in sound" , "Jarring" , "Ring tag (anag.)" .)