Flustered following circuit of racetrack, possibly discontented (6)

I believe the answer is:

flappy

'flustered' is the definition.
(both can mean distressed)

'following circuit of racetrack possibly discontented' is the wordplay.
'following' becomes 'f.' (used when citing page numbers etc).
'circuit of racetrack' becomes 'lap' (a lap is one circuit of a racetrack).
'discontented' suggests removing the centre.
'possibly' with its centre taken out is 'py'.
'f'+'lap'+'py'='FLAPPY'

I've seen this clue in The Telegraph.

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