Bond's boss to query disguise (4)
I believe the answer is:
mask
'disguise' is the definition.
(masking is a kind of disguising)
'bond's boss to query' is the wordplay.
'bond's boss' becomes 'm' (M is the head of MI6 in the James Bond series).
'to query' becomes 'ask'.
'm'+'ask'='MASK'
(Other definitions for mask that I've seen before include "Face covering; disguise" , "Face-cover" , "Screen" , "cloak" , "Visor; disguise" .)