Withdrew soldiers given medical attention? (9)
I believe the answer is:
retreated
'withdrew' is the definition.
('retreat' can be a synonym of 'withdraw')
'soldiers given medical attention?' is the wordplay.
'soldiers' becomes 'RE' (Royal Engineers).
'given medical attention?' becomes 'treated' (gave treatment).
're'+'treated'='RETREATED'
(Other definitions for retreated that I've seen before include "Gave up ground" , "Retired" , "Went back" , "pulled back" , "Left" .)