Whereby some are entitled to celebrate the arrival of the monarch (8,7)

'whereby some are entitled to celebrate' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'the arrival of the monarch' is the wordplay.
I cannot really understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
'of' could be 'o' and 'o' is present in the answer.
'monarch' could be 'r' (abbreviation for rex, king in Latin) and 'r' is found in the answer.
This explanation may well be incorrect...