Soldiers gave up and withdrew (7)
I believe the answer is:
receded
'withdrew' is the definition.
('recede' can be a synonym of 'withdraw')
'soldiers gave up' is the wordplay.
'soldiers' becomes 'RE' (Royal Engineers).
'gave up' becomes 'ceded' ('cede' can be a synonym of 'give up').
're'+'ceded'='RECEDED'
'and' acts as a link.
(Other definitions for receded that I've seen before include "Moved backwards" , "Pulled back" , "Went back or retreated" , "Fell back" , "Went back as hairline may" .)