Scrooge Mike is with monarch (5)
I believe the answer is:
miser
'scrooge' is the definition.
(Dickens' Ebenezer Scrooge is a miser)
'mike is with monarch' is the wordplay.
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'with' is a charade indicator (letters next to each other).
'monarch' becomes 'er' (abbreviation for Elizabeth Regina, British Queen).
'm'+'is'+'er'='MISER'
(Other definitions for miser that I've seen before include "Penny-pinching person like Scrooge" , "Pinchpenny" , "Mean individual" , "Wealth hoarder" , "One of the people who spend least" .)