Arrangement of topsail involves one working regarding placement (10)

I believe the answer is:

positional

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'arrangement of topsail involves one working regarding placement' is the definition.
I can't judge whether this defines the answer.

'arrangement of topsail involves one working' is the wordplay.
'arrangement of' is an anagram indicator.
'involves' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'working' becomes 'on' (e.g. a machine is working or on).
'topsail' is an anagram of 'posital'.
'i'+'on'='ion'
'posital' placed around 'ion' is 'POSITIONAL'.

Can you help me to learn more?

(Another definition for positional that I've seen is " Relating to disposition".)

I've seen this clue in The Independent.

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