Vet's mask (6)
I believe the answer is:
screen
I believe this is a double definition.
'vet's' is the first definition.
(both can mean to check or investigate)
'mask' is the second definition.
(I've seen this before)
(Other definitions for screen that I've seen before include "Upright partition" , "Protective frame" , "Movable partitions" , "Cover - cinema" , "Block out" .)