The most common and most likely answer to this crossword clue is the 10 letter word QUARANTINE
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More clues leading to the result QUARANTINE
Buddy explains!

The straight part
We know that "unwelcome end to foreign holiday" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case unwelcome end to foreign holiday = quarantine.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does QUARANTINE mean?
QUARANTINE noun- The desert in which Christ fasted for 40 days according to the Bible.
- A grace period of 40 days during which a widow has the right to remain in her dead husband's home, regardless of the inheritance.
- A sanitary measure to prevent the spread of a contagious plague by isolating those believed or feared to be infected.
- Such official detention of a ship at or off port due to suspicion that it may be carrying a contagious disease aboard.
- A certain place for isolating persons suspected of suffering from a contagious disease.
- A certain period of time during which a person is isolated to determine whether they've been infected with a contagious disease.
- (by extension) Any rigorous measure of isolation, regardless of the reason.
- A record system kept by port health authorities in order to monitor and prevent the spread of contagious diseases.
- A place where email messages or other files which are suspected of harboring a computer virus are stored.
- To retain in obligatory isolation or separation, as a sanitary measure to prevent the spread of contagious disease.
- To put in isolation as if by quarantine