Possessive? It is! (3)
I believe the answer is:
its
'possessive?' is the definition.
(I've seen this in another clue)
'it is' is the wordplay.
I cannot quite understand how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found within the answer.
'is' is found in 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 its that I've seen before include "Belonging to a particular thing" , "Another form of 'tis" , "Sit (anag.)" , "Neuter possessive pronoun" , "The thing's" .)