Rabbi led reformation although he never prepared a speech (2-6)

I believe the answer is:

ad-libber

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'he never prepared a speech' is the definition.
The definition suggests a singular noun but the answer is not.

'rabbi led reformation' is the wordplay.
'reformation' is an anagram indicator.
'rabbi'+'led'='rabbiled'
'rabbiled' anagrammed gives 'AD-LIBBER'.

'although' is the link.

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I've seen this clue in The Irish Times.

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