Brilliant writer hugged by boss, old American (10)

I believe the answer is:

stupendous

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'brilliant writer hugged by boss old american' is the definition.
I can't judge whether this defines the answer.

'brilliant writer hugged by boss old american' is the wordplay.
'brilliant writer' becomes 'pen' (something which writes. I am not sure about the 'brilliant' bit.).
'hugged by' means one lot of letters goes inside another (I've seen this in other clues).
'boss' becomes 'stud' (both can mean a metal decoration).
'old' becomes 'o' (abbreviation).
'american' becomes 'US' (United States).
'pen' put inside 'stud' is 'stupend'.
'stupend'+'o'+'us'='STUPENDOUS'

Can you help me to learn more?

(Other definitions for stupendous that I've seen before include "Extremely impressive" , "Phenomenal" , "Astounding" , "Astoundingly huge" .)

I've seen this clue in The Telegraph.

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