Rage shown by monarch: tough old bird (6)
I believe the answer is:
boiler
'tough old bird' is the definition.
(I've seen this before)
'rage shown by monarch' is the wordplay.
'rage' becomes 'boil' (I've seen this in another clue).
'shown by' says to put letters next to each other.
'monarch' becomes 'ER' (abbreviation for Elizabeth Regina, British Queen).
'boil'+'er'='BOILER'
(Other definitions for boiler that I've seen before include "tough old bird" , "Container to heat water or tough fowl" , "Tank for heating water" , "Water heater" , "Water-heater" .)