Try to gain favour from army person, we hear. leading to facing this? (5,7)
I believe the answer is:
court martial
'person we hear leading to facing this?' is the definition.
The definition suggests a singular noun which matches the answer.
'try to gain favour from army' is the wordplay.
'try to gain favour from' becomes 'court' (to court someone is to try to win their favour).
'army' becomes 'martial'.
'court'+'martial'='COURT-MARTIAL'
(Other definitions for court martial that I've seen before include "Try, in service" , "Decider on military law" , "Military trial" , "Military justice" , "Soldiers tried here" .)