Go on salt concoction to restrict opening of blood vessels (9)

I believe the answer is:

longboats

'vessels' is the definition.
(longboat is a kind of vessel)

'go on salt concoction to restrict opening of blood' is the wordplay.
'concoction' indicates anagramming the letters.
'to restrict' indicates putting letters inside.
'opening of' indicates taking the first letters.
The initial letter of 'blood' is 'b'.
'go'+'on'+'salt'='goonsalt'
'goonsalt' is an anagram of 'longoats'.
'longoats' enclosing 'b' is 'LONGBOATS'.

I've seen this clue in The Independent.

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