The most common and most likely answer to this crossword clue is the 8 letter word OUTMATCH
I've seen this crossword clue in The Guardian
O
U
T
M
A
T
C
H
More clues leading to the result OUTMATCH
Buddy explains!

The straight part
We know that "better" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case better = outmatch.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 OUTMATCH mean?
OUTMATCH verb- To surpass or be better than something or someone else