The smallest note - a fifty (7)

I believe the answer is:

minimal

'the smallest' is the definition.
(I've seen this before)

'note a fifty' is the wordplay.
'note' becomes 'minim' (type of musical note).
'fifty' becomes 'l' (Roman numeral).
'minim'+'a'+'l'='MINIMAL'

(Other definitions for minimal that I've seen before include "Very small, the least possible (7)" , "Very little" , "barely worth considering" , "Least possible; negligible" , "Token" .)

I've seen this clue in the Evening Standard.

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