Irish university staff member apparently about 150! (6)

I believe the answer is:

declan

I'm a little stuck... Click here to teach me more about this clue!

'irish university staff member' is the definition.
I don't know anything about this answer so I can't tell whether this works.

'apparently about 150' is the wordplay.
'apparently' becomes 'dean' (I can't justify this - if you can you should believe this answer much more).
'about' indicates putting letters inside.
'd50' becomes 'CL' (Roman numerals).
'dean' placed around 'cl' is 'DECLAN'.

Can you help me to learn more?

(Another definition for declan that I've seen is " Irish saint?".)

I've seen this clue in the Evening Standard.

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