Guard portal that's moving (6)

I believe the answer is:

patrol

'guard' is the definition.
(I know that patrol is a kind of guard)

'portal that's moving' is the wordplay.
'that's moving' is an anagram indicator (letters are moved around).
'portal' is an anagram of 'PATROL'.

(Other definitions for patrol that I've seen before include "Portal for those on security duty" , "Reconnaissance unit" , "Part of Scouts troop" , "Small group of Guides/Scouts" , "military unit" .)

I've seen this clue in The Sun.

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