Something for graduation which is good to have (4)

I believe the answer is:

gown

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'something for graduation which' is the definition.
I can't tell whether this defines the answer.

'good to have' is the wordplay.
'good' becomes 'g' (abbreviation).
'to have' becomes 'own' (to have something is to own it).
'g'+'own'='GOWN'

'is' is the link.

Can you help me to learn more?

(Other definitions for gown that I've seen before include "Dress for formal occasions" , "Academic attire" , "Shift" , "An evening dress" , "Academic robe" .)

I've seen this clue in The Telegraph.

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