Popular countertenor once going about with one persistently present (9)

I believe the answer is:

indweller

'one persistently present' is the definition.
(someone who dwells in a place)

'popular countertenor once going about with' is the wordplay.
'popular' becomes 'in'.
'countertenor once' becomes 'deller' (singer Alfred Deller).
'going about' means one lot of letters goes inside another.
'with' becomes 'w' (abbreviation).
'deller' enclosing 'w' is 'dweller'.
'in'+'dweller'='INDWELLER'

(Another definition for indweller that I've seen is " Resident".)

I've seen this clue in The Times.

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