Revive soldiers hard peasant knocked over (7)
I believe the answer is:
refresh
'revive' is the definition.
(I've seen this before)
'soldiers hard peasant knocked over' is the wordplay.
'soldiers' becomes 're' (Royal Engineers).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'peasant' becomes 'serf' (I've seen this in another clue).
'knocked over' is a reversal indicator.
'h'+'serf'='hserf'
'hserf' in reverse letter order is 'fresh'.
're'+'fresh'='REFRESH'
(Other definitions for refresh that I've seen before include "Breathe new life into" , "Enliven once more" , "Give drink to" , "Stimulate as by reminding, or top up drink" , "Invigorate -- her serf (anag)" .)