Impulsive monarch wants some bacon (6)
I believe the answer is:
rasher
'some bacon' is the definition.
(I've seen this before)
'impulsive monarch' is the wordplay.
'impulsive' becomes 'rash' (I've seen this before).
'monarch' becomes 'ER' (abbreviation for Elizabeth Regina, British Queen).
'rash'+'er'='RASHER'
'wants' acts as a link.
(Other definitions for rasher that I've seen before include "type of food" , "More imprudent" , "Thin slice of bacon" , "American fish" , "More foolhardy than a slice of bacon" .)