What emerges from enquiry upsets soldier, losing heart (6)
I believe the answer is:
report
'what emerges from enquiry' is the definition.
(an enquiry's findings may be shown in a report)
'upsets soldier losing heart' is the wordplay.
'upsets' says the letters should be written backwards.
'soldier' becomes 'trooper' (trooper is a kind of soldier).
'losing heart' suggests removing the centre.
'trooper' with its middle taken out is 'troper'.
'troper' reversed gives 'REPORT'.
(Other definitions for report that I've seen before include "Complain about; noise" , "Explosion" , "Statement - sound of a gun firing" , "Give an account" , "Pupil's assessment" .)