Short lament by soldier’s lover (8)
I believe the answer is:
paramour
'lover' is the definition.
(term for a lover)
'short lament by soldier's' is the wordplay.
I cannot really understand how this works, but
'soldier' could be 'para' (short for paratrouper) and 'para' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for paramour that I've seen before include "A married person's secret lover" , "wife's toy boy, for example" , "A lover, illicit perhaps" , "Kept woman" , "Lover, usually illicit" .)