The most common and most likely answer to this crossword clue is the 5 letter word OWING
I've seen this crossword clue in The Daily Telegraph
O
W
I
N
G
More clues leading to the result OWING
- Outstanding old part of house
- Outstanding all-rounder finally eliminated from water sport
- Old part of building is outstanding
- Outstanding victory secured by own goal
- Having Pole chucked out leaves one unsettled
- Due to be in old part of mansion
- Outstanding victory defensive blunder secures
- Outstanding score for other side securing victory
- Outstanding playing cello perhaps, but not bass
- Outstanding to keep good one taken inside
Buddy explains!

The straight part
We know that "Outstanding" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case outstanding = owing.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 OWING mean?
OWING verb- To be under an obligation to give something back to someone or to perform some action for someone.
- To have debt; to be in debt.
- Still to be paid; owed as a debt.