Pith helmet: most superior one (4)

I believe the answer is:

topi

'pith helmet' is the definition.
(synonyms)

'most superior one' is the wordplay.
'most superior' becomes 'top'.
'one' becomes 'i' (Roman numeral).
'top'+'i'='TOPI'

(Other definitions for topi that I've seen before include "African antelope" , "that goes ahead" , "Pith helmet" , "Pith-helmet" , "cover in the heat" .)

I've seen this clue in The Times.

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