Rapacious government leader, shrill (6)
I believe the answer is:
greedy
'rapacious' is the definition.
(thesaurus)
'government leader shrill' is the wordplay.
'leader' indicates taking the first letters.
'shrill' becomes 'reedy' (I've seen this before).
The initial letter of 'government' is 'g'.
'g'+'reedy'='GREEDY'
(Other definitions for greedy that I've seen before include "pig!" , "Grasping" , "Having a voracious appetite" , "Very eager to get" , "Keen" .)