The most common and most likely answer to this crossword clue is the 2 plus 3 letter word IN PUP
I've seen this crossword clue in Financial Times
I
N
P
U
P
More clues leading to the result IN PUP
- Where drinkers are mostly parking, about to drop litter
- Is not prudent using paper at first: expecting litter!
- Getting ready to drop litter?
- Expectant, perhaps, as Afghan model lowers top
- About to drop glamour girl adjusting top
- Some mop up, niggling over carrying litter
- a So new setters to debut soon? First signs of interference, Notabilis packs up!
Buddy explains!

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.