Reserved band after soldiers backed it (8)
I believe the answer is:
retiring
'reserved' is the definition.
(I've seen this before)
'band after soldiers backed it' is the wordplay.
'band' becomes 'ring' (synonyms).
'after' says to put letters next to each other.
'soldiers' becomes 'RE' (Royal Engineers).
'backed' says the letters should be written backwards.
'it' backwards is 'ti'.
're'+'ti'='reti'
'ring' put after 'reti' is 'RETIRING'.
(Other definitions for retiring that I've seen before include "Bashful" , "of unobtrusive aspect" , "Shy and fond of being on one's own" , "Shy, avoiding company" , "Shy; stopping work" .)