Doctor about to get extra (4)

I believe the answer is:

'extra' is the definition.
(both can mean additional)

'doctor about' is the wordplay.
'doctor' becomes 'mo' (medical officer).
'about' becomes 're' ('re' means regarding or about).
'mo'+'re'='MORE'

'to get' acts as a link.

(Other definitions for more that I've seen before include "Extra (for Sir Thomas?)" , "A greater amount" , "Greater quantity or number" , "See 9" , "To a greater extent" .)

I've seen this clue in The Mirror.

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