Embarrasses fellow endlessly, then smiles (8)

I believe the answer is:

chagrins

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'embarrasses' is the definition.

'fellow endlessly then smiles' is the wordplay.
'fellow' becomes 'chap' ('chap' can be a synonym of 'fellow').
'endlessly' means to remove the last letter.
'then smiles' becomes 'grins' (grinning is a kind of smiling. I am not sure about the 'then' bit.**).
'chap' with its last letter removed is 'cha'.
'cha'+'grins'='CHAGRINS'

Can you help me to learn more?

(Another definition for chagrins that I've seen is " disappoints".)

I've seen this clue in The Telegraph.

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