Good service, tennis ace (4)

I believe the answer is:

graf

'tennis ace' is the definition.
(tennis player Steffi Graf)

'good service' is the wordplay.
'good' becomes 'g' (abbreviation).
'service' becomes 'RAF' (Royal Air Force).
'g'+'raf'='GRAF'

(Other definitions for graf that I've seen before include "German count - German tennis player" , "Steffi --, tennis champion" , "Noted tennis player" , "Steffi --, tennis player" , "Seven-times women's Wimbledon champion, b. 1969" .)

I've seen this clue in The Guardian.

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