Animosity private soldier articulated (7)
I believe the answer is:
rancour
'animosity' is the definition.
(I've seen this before)
'private soldier articulated' is the wordplay.
'private soldier' becomes 'ranker' (I've seen this before).
'articulated' shows a homophone (sound like).
'ranker' is a homophone of 'RANCOUR'.
(Other definitions for rancour that I've seen before include "Deep-seated bitterness" , "Bitter feeling or ill-will" , "Virulence" , "Hard feelings" , "Spiteful ill-feeling" .)