In test, males frequently getting compassion in critical period (6,2,5)
I believe the answer is:
moment of truth
'critical period' is the definition.
(a decisive or critical moment)
'in test males frequently getting compassion' is the wordplay.
'in' indicates putting letters inside.
'test' becomes 'MOT' (as in an MOT test for a vehicle).
'males' becomes 'men' (man is a kind of male).
'frequently' becomes 'oft' (synonyms).
'getting compassion' becomes 'ruth' (I am not sure about this - if you are sure you should believe this answer much more).
'mot' going around 'men' is 'moment'.
'moment'+'oft'+'ruth'='MOMENT OF TRUTH'
'in' is the link.
(Other definitions for moment of truth that I've seen before include "From the mutton (anag) - significant point in time" , "spin-doctor aims to avoid?" , "Critical juncture" , "Critical point" , "Crucial point in time on which much depends" .)