Sedative mercenary carried around Romania (7)
I believe the answer is:
veronal
'sedative' is the definition.
(veronal is a kind of sedative)
'mercenary carried around romania' is the wordplay.
'mercenary' becomes 'venal' (I've seen this before).
'carried around' is an insertion indicator.
'romania' becomes 'ro' (international vehicle registration code).
'venal' placed around 'ro' is 'VERONAL'.
(Other definitions for veronal that I've seen before include "Sedative" , "Barbiturate (from Italian city?)" , "draught?" .)