Overkeen supporter in fact heading for Arsenal ground (7)

I believe the answer is:

fanatic

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'overkeen supporter' is the definition.
I can't judge whether this definition defines the answer.

'in fact heading for arsenal ground' is the wordplay.
'heading for' says to take the initial letters.
'ground' is an anagram indicator ('grind' the letters into a new form).
The initial letter of 'arsenal' is 'a'.
'in'+'fact'+'a'='infacta'
'infacta' anagrammed gives 'FANATIC'.

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(Other definitions for fanatic that I've seen before include "crank" , "Narrow-minded enthusiast" , "Obsessive enthusiast" , "Freak" , "Person filled with excessive zeal for cause" .)

I've seen this clue in The Telegraph.

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