Fluctuating, with NI county ahead at first (2-3-4)

I believe the answer is:

up-and-down

'fluctuating' is the definition.
(up and down can mean fluctuating or changing)

'with ni county ahead at first' is the wordplay.
'with' becomes 'and'.
'ni county' becomes 'down' (County Down in Northern Ireland).
'ahead' becomes 'up' (similar in meaning).
'at first' means one lot of letters go next to another.
'and'+'down'='anddown'
'anddown' after 'up' is 'UP-AND-DOWN'.

I've seen this clue in The Telegraph.

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