Climbing mountain, carefully note alternative strategy (4,1)

I believe the answer is:

plan b

'alternative strategy' is the definition.
(I've seen this in another clue)

'climbing mountain carefully note' is the wordplay.
'climbing' is a reversal indicator (in a down clue, letters climb up).
'mountain' becomes 'alp' (the Alps are a mountain range).
'carefully note' becomes 'NB' (short for 'nota bene', note well).
'alp' in reverse letter order is 'pla'.
'pla'+'nb'='PLAN B'

I've seen this clue in The Times.

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