The most common and most likely answer to this crossword clue is the 7 letter word SELLOUT
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Buddy explains!
The straight part
We know that "when there are no tickets left" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case when there are no tickets left = sellout.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 SELLOUT mean?
SELLOUT noun- An action in which principles are compromised for financial gain.
- A person who compromises his or her principles for financial gain.
- The selling of an entire stock of something, especially tickets for an entertainment or sports event.