Token working in support of military takeover (6)
I believe the answer is:
coupon
'token' is the definition.
(I've seen this before)
'working in support of military takeover' is the wordplay.
'working' becomes 'on' (on can mean working or activated).
'in support of' means one lot of letters go next to another (in a down clue, some letters hold others up).
'military takeover' becomes 'coup' (a coup d'etat by the military).
'on' put after 'coup' is 'COUPON'.
(Other definitions for coupon that I've seen before include "Token" , "Entry form" , "betting slip" , "Voucher or ticket" , "means to buy goods" .)