Fellow at hen party - so unenlightened! (7)

I believe the answer is:

heathen

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'unenlightened' is the definition.
(thesaurus)

'fellow at hen' is the wordplay.
'fellow' becomes 'he' ('he' refers to a man).
'he'+'at'+'hen'='HEATHEN'

'party so' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.

Can you help me to learn more?

(Other definitions for heathen that I've seen before include "Non-believer" , "Infidel, pagan" , "Person lacking culture or moral principles" , "Uncultured" , "Godless person" .)

I've seen this clue in the Sydney Morning Herald.

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