Criterion, standard (10)
I believe the answer is:
touchstone
I believe this is a double definition.
'criterion' is the first definition.
(I know that criterion can be written as touchstone)
'standard' is the second definition.
(I know that standard can be written as touchstone)
(Other definitions for touchstone that I've seen before include "jester" , "Character in As You Like It" , "forest-dweller" , "Jasper" , "stage clown" .)