The most common and most likely answer to this crossword clue is the 5 letter word SURER
I've seen this crossword clue in The Times
S
U
R
E
R
More clues leading to the result SURER
- More certain resistance stops one taking legal action
- More confident underwriter drops in
- More confident as litigant, suppressing resistance
- Man on board, fellow going to be more confident
- As a result of the economic present, charges will rise
- Unintroduced loan shark is more confident
- More certain ruse works catching raw beginner
- Treasure robber, to some extent, is more certain
Buddy explains!

The straight part
We know that "More confident" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case more confident = surer.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 SURER mean?
SURER adjective- Physically secure and certain, non-failing, reliable.
- Certain in one's knowledge or belief.
- Certain to act or be a specified way.
- Free from danger; safe; secure.
- Betrothed; engaged to marry.