The doctor again gives extra (4)

I believe the answer is:

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

'the doctor again' is the wordplay.
'the doctor' becomes 'mo' (medical officer).
'again' becomes 're' (prefix meaning 'again').
'mo'+'re'='MORE'

'gives' is the link.

(Other definitions for more that I've seen before include "victim of Henry" , "To a greater extent" , "Additional or larger amount" , "Greater quantity or number" , "A greater amount" .)

I've seen this clue in The Irish Independent.

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