A consequence of soldiers' drumming (12)
I believe the answer is:
repercussion
'a consequence' is the definition.
(repercussion is a kind of consequence)
'soldiers' drumming' is the wordplay.
'soldiers'' becomes 're' (I've seen this in other clues).
'drumming' becomes 'percussion' ('percussion' can be a synonym of 'drumming').
're'+'percussion'='REPERCUSSION'
'of' acts as a link.
(Other definitions for repercussion that I've seen before include "Impact" , "Indirect consequence of some action" , "Indirect effect; echo" , "Backlash" , "Unintended consequence" .)