The most common and most likely answer to this crossword clue is the 6 letter word LOSING
I've seen this crossword clue in The Guardian
L
O
S
I
N
G
More clues leading to the result LOSING
- Lacking bit of custom, shutting down
- Opposed to opening, dropping, opening, dropping?
- Heather must conceal exceptionally large behind
- Defeat looks far from good in the record (6
- See Carol trailing in game
- Down wrong in record
- What is wrong in record being beaten?
- Don’t start shutting down
- Going down having wrong entry in ship’s record
- Down South I ache going around
Buddy explains!

The straight part
We know that "Defeat" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case defeat = losing.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 LOSING mean?
LOSING verb- To cause (something) to cease to be in one's possession or capability due to unfortunate or unknown circumstances, events or reasons.
- To wander from; to miss, so as not to be able to find; to go astray from.
- To fail to win (a game, competition, trial, etc).
- To be unable to follow or trace (somebody or something) any longer.
- To cause (somebody) to be unable to follow or trace one any longer.
- To cease exhibiting; to overcome (a behavior or emotion).
- To shed, remove, discard, or eliminate.
- Of a clock, to run slower than expected.
- (ditransitive) To cause (someone) the loss of something; to deprive of.
- To fail to catch with the mind or senses; to miss.
- To cause to part with; to deprive of.
- The process by which something is lost; a loss.
- That loses or has lost.