All in Schengen upset about Hungary's immigration barrier (7,7)

I believe the answer is:

english channel

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'immigration barrier' is the definition.
The definition suggests a singular noun which matches the answer.

'all in schengen upset about hungary's' is the wordplay.
'upset' is an anagram indicator.
'about' is an insertion indicator.
'hungary' becomes 'H' (abbreviation used in vehicle registration codes).
'all'+'in'+'schengen'='allinschengen'
'allinschengen' with letters rearranged gives 'englischannel'.
'englischannel' placed around 'h' is 'ENGLISH CHANNEL'.

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(Another definition for english channel that I've seen is " distances us from France".)

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