Discharged soldiers left and relaxed (8)
I believe the answer is:
released
'discharged' is the definition.
('released' can be a synonym of 'discharged')
'soldiers left and relaxed' is the wordplay.
'soldiers' becomes 're' (Royal Engineers).
'left' becomes 'l' (common abbreviation).
'and' says to put letters next to each other.
'relaxed' becomes 'eased' (I've seen this before).
're'+'l'+'eased'='RELEASED'
(Other definitions for released that I've seen before include "Sent from prison" , "Let out - let out again" , "Liberated" , "Set free" , "free after imprisonment?" .)