Partisan soldier hides diamonds in this place (8)
I believe the answer is:
adherent
'partisan' is the definition.
(I've seen this before)
'soldier hides diamonds in this place' is the wordplay.
'soldier' becomes 'ant' (I've seen this before).
'hides' is an insertion indicator.
'diamonds' becomes 'd' (abbreviation in bridge say).
'in this place' becomes 'here' ('here' can be a synonym of 'in this place').
'd'+'here'='dhere'
'ant' placed around 'dhere' is 'ADHERENT'.
(Other definitions for adherent that I've seen before include "Person supporting" , "Dedicated supporter" , "Sticking; partisan" , "Supporter, follower" , "Loyal follower - sticks close" .)