Some fort built by first-rate type (8)

I believe the answer is:

foremost

I'm a little stuck... Click here to teach me more about this clue!

'some fort built by first-rate type' is the definition.
I can't tell whether this definition defines the answer.

'some fort built' is the wordplay.
'built' indicates an anagram.
'some'+'fort'='somefort'
'somefort' with letters rearranged gives 'FOREMOST'.

Can you help me to learn more?

(Other definitions for foremost that I've seen before include "Most prominent" , "First in rank" , "First in time, place or order" , "Pre-eminent" , "premier" .)

I've seen this clue in the Irish Times and the Irish Times (Crosaire).

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