Familiar light-hearted American (3)

I believe the answer is:

gus

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'familiar' is the definition.
Both the answer and definition are singular nouns.
Maybe they are linked in a way I don't understand?

'light-hearted american' is the wordplay.
'hearted' says to take the centre.
'american' becomes 'US' (abbreviation for United States).
The central letter of 'light' is 'g'.
'g'+'us'='GUS'

Can you help me to learn more?

(Other definitions for gus that I've seen before include "Augustus (dim.)" , "T. S. Eliot's theatre cat" .)

I've seen this clue in the Evening Standard.

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