Unmasked once questions are put (7)
I believe the answer is:
exposed
'unmasked' is the definition.
(I've seen this in another clue)
'once questions are put' is the wordplay.
I cannot really understand how this works, but
'once' could be 'ex' (prefix meaning former or onetime) and 'ex' is located in the answer.
'are' could be 'posed' (posing is a kind of being) and 'posed' is found within the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for exposed that I've seen before include "Shown up" , "in the nude" , "Unmasked, revealed" , "Brought to light" , "Showed up" .)