The most common and most likely answer to this crossword clue is the 4 plus 5 letter word TIME LIMIT
I've seen this crossword clue in The Guardian
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More clues leading to the result TIME LIMIT
- Item revised and bound, making deadline
- Moved tile 1mm — it fixed window
- Farron and Henman face off over priest setting deadline
- Magazine writer’s breaking reading deadline
- One minute after the first Spice Girl gets into Bristol, given this no longer possible?
- Magazine bound to make
- Stir a lot of citrus fruit, and appeal for date to finish
- Bond holding masculine student in unnamed Cambridge college for period allowed
Buddy explains!

The straight part
We know that "fixed window" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fixed window = time limit.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 TIME LIMIT mean?
TIME LIMIT noun- A time by which something must finish
- A duration beyond which something may not exceed
- To set a time limit on.