Biting wit can have one in tears (6)
I believe the answer is:
satire
'tears' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'biting wit can have one in' is the wordplay.
'biting wit can' becomes 'ir' (I am not sure about this - if you are sure you should believe this answer much more).
'have' becomes 'sate' (sating is a kind of having).
'one in' means one lot of letters goes inside another.
'ir' going inside 'sate' is 'SATIRE'.
Can you help me to learn more?
(Other definitions for satire that I've seen before include "sort of ironic humour" , "Jonathan Swift's forte?" , "Novel or play that ridicules social failings" , "Mocking humour" , "Caustic comments" .)