Marshal in the Nine Years War (3)
I believe the answer is:
ney
'marshal' is the definition.
(I've seen this in other clues)
'in the nine years war' is the wordplay.
'in' says the answer is hidden in the clue.
'NEY' can be found hidden inside 'nine years war'.
(Other definitions for ney that I've seen before include "French marshal sound negitative" , "One of Napoleon's marshals" , "French soldier" .)