The most common and most likely answer to this crossword clue is the 9 letter word FORTNIGHT
I've seen this crossword clue in The Guardian
F
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More clues leading to the result FORTNIGHT
- Contended with horseman, say, several days
- Castle and another piece ignoring king for some time
- Struggle to cover up torn pants every couple of weeks
- Keep hours of darkness for two weeks
- Period when was jousting, reportedly?
- Two weeks in secure accommodation near the beginning of term
- Keep dark for a set period
- Was boxing champion, say, for two weeks
- Badly torn in struggle that lasts some time
- Torn apart, crushed by conflict for some time
Buddy explains!

The straight part
We know that "couple of weeks" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case couple of weeks = fortnight.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 FORTNIGHT mean?
FORTNIGHT noun- A period of 2 weeks.