Gardener I'd fired was a doppelgänger! (4-6)

I believe the answer is:

dead-ringer

'a doppelganger' is the definition.
(thesaurus)

'gardener i'd fired' is the wordplay.
'fired' indicates anagramming the letters (I've seen this in other clues).
'gardener'+'id'='gardenerid'
'gardenerid' is an anagram of 'DEAD-RINGER'.

'was' acts as a link.

I've seen this clue in the Sydney Morning Herald.

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