Response from soldiers with instruction to shoot (8)
I believe the answer is:
reaction
'response' is the definition.
(I know that response can be written as reaction)
'soldiers with instruction to shoot' is the wordplay.
'soldiers' becomes 're' (Royal Engineers).
'with' says to put letters next to each other.
'instruction to shoot' becomes 'action' ('action' is an instruction to shoot on a film set).
're'+'action'='REACTION'
'from' acts as a link.
(Other definitions for reaction that I've seen before include "Force" , "Result of stimulus" , "Creation found in response to event" , "Chemical change or response" , "counter-revolution" .)