Strongly anger unionists, being enthusiastic (5,2)

I believe the answer is:

fired up

'enthusiastic' is the definition.

'strongly anger unionists' is the wordplay.
'strongly' becomes 'f' (abbreviation for 'forte', literally 'strong').
'anger' becomes 'ire' ('ire' can be a synonym of 'anger').
'unionists' becomes 'dup' (Democratic Unionist Party).
'f'+'ire'+'dup'='FIRED UP'

'being' is the link.

I've seen this clue in The Guardian.

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