Rage no good pursuing a monarch (5)
I believe the answer is:
anger
'rage' is the definition.
(I've seen this in another clue)
'no good pursuing a monarch' is the wordplay.
'no good' becomes 'ng' (abbreviation for no and good).
'pursuing' says to put letters next to each other.
'monarch' becomes 'er' (abbreviation for Elizabeth Regina, British Queen).
'ng' put after 'a' is 'ang'.
'ang'+'er'='ANGER'
(Other definitions for anger that I've seen before include "Wrath, ire" , "wind up?" , "Nettle" , "Deadly sin" , "Extreme annoyance" .)