Sadness quiet girl displays about old soldier going west (9)
I believe the answer is:
poignancy
'sadness' is the definition.
(poignancy is a kind of sadness)
'quiet girl displays about old soldier going west' is the wordplay.
I cannot quite understand how this works, but
'quiet' could be 'p' (music symbol for 'piano') and 'p' is found within the answer.
'girl' could be 'nancy' and 'nancy' is present in the answer.
'old' could be 'o' (common abbreviation eg in OE for Old English) and 'o' is found within the answer.
This explanation may well be incorrect...
(Other definitions for poignancy that I've seen before include "sentiment" , "such a rueful thing" , "Quality that can touch or move" , "Sadness" .)