Sweet about vacuous selfie one shows off (5)

I believe the answer is:

pseud

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'one shows off' is the definition.
I can't tell whether this definition defines the answer.

'sweet about vacuous selfie' is the wordplay.
'sweet' becomes 'pud' (pud is a kind of sweet).
'about' is an insertion indicator.
'vacuous' suggests removing the centre.
'selfie' with its centre removed is 'se'.
'pud' placed around 'se' is 'PSEUD'.

Can you help me to learn more?

(Other definitions for pseud that I've seen before include "Pretentious sort" , "Pretentious fraud" , "pretentious woman" , "Pretentious person (colloq.)" , "Fraud -- dupes (anag)" .)

I've seen this clue in The Telegraph.

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