The most common and most likely answer to this crossword clue is the 7 letter word FIZZLES
F
I
Z
Z
L
E
S
Buddy explains!

The straight part
We know that "comes to nought" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case comes to nought = fizzles.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 FIZZLES mean?
FIZZLES verb- To sputter or hiss.
- To decay or die off to nothing; to burn out; to end less successfully than previously hoped.