Sense mood to accept second criterion (10)
I believe the answer is:
touchstone
'criterion' is the definition.
('touchstone' can be a synonym of 'criterion')
'sense mood' is the wordplay.
'sense' becomes 'touch' (touch is a kind of sense).
'mood' becomes 'stone' (I can't justify this - if you can you should believe this answer much more).
'touch'+'stone'='TOUCHSTONE'
'to accept second' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for touchstone that I've seen before include "Shakespearean character" , "stage clown" , "forest-dweller" , "Character in As You Like It" , "jester" .)