Discharge English soldier that's hit volunteers from the south (9)
I believe the answer is:
emanation
'discharge' is the definition.
(I've seen this before)
'english soldier that's hit volunteers from the south' is the wordplay.
'english' becomes 'e' (abbreviation).
'soldier' becomes 'man' (I've seen this before).
'that's hit' becomes 'noi' (I can't justify this - if you can you should give a lot more credence to this answer).
'volunteers' becomes 'ta' (abbreviation for Territorial Army).
'from the south' is a reversal indicator (in a down clue, letters go up).
'noi'+'ta'='noita'
'noita' reversed gives 'ation'.
'e'+'man'+'ation'='EMANATION'
Can you help me to learn more?
(Other definitions for emanation that I've seen before include "Issue" , "Something produced from a source" , "discharge" , "Something flowing out from a source" , "Something given off" .)