Material implicating Government of King? (5)
I believe the answer is:
regal
'of king?' is the definition.
'material implicating government' is the wordplay.
'material' becomes 'real' ('real' is associated in meaning with 'material').
'implicating' indicates putting letters inside.
'government' becomes 'g'.
'real' going around 'g' is 'REGAL'.
(Other definitions for regal that I've seen before include "Portable organ" , "fit for the Queen" , "Befitting a monarch" , "Magnificent, dignified" , "Kingly or queenly" .)