One who's up robing duke with unusual grandeur (9)

I believe the answer is:

undergrad

'one who's up robing' is the definition.
(undergrads wear robes at graduation ceremonies)

'duke with unusual grandeur' is the wordplay.
'duke' becomes 'd' (abbreviation).
'with' is a charade indicator (letters next to each other).
'unusual' is an anagram indicator.
'grandeur' with letters rearranged gives 'undergra'.
'd' after 'undergra' is 'UNDERGRAD'.

(Another definition for undergrad that I've seen is " Learner".)

I've seen this clue in The Times.

Want a hint initially instead of a full solution? Install my app