Stroke, fantastic cut, is making boundary (5)

I believe the answer is:

ictus

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

'fantastic cut is making boundary' is the wordplay.
'cut is' anagrams to 'ICTUS'.
But, I am not sure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for ictus that I've seen before include "Is cut (anag.)" , "recurrence of disease results" , ""fit"" , "Seizure" , "Sudden attack" .)

I've seen this clue in The Times.

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