The most common and most likely answer to this crossword clue is the 5 plus 2 plus 3 plus 3 letter word CHAMP AT THE BIT
I've seen this crossword clue in The Guardian
C
H
A
M
P
A
T
T
H
E
B
I
T
More clues leading to the result CHAMP AT THE BIT
- Be impatient winner: rather gripping series of races against that fellow
- Winner that I bet is disposed to be impatient
- Showing impatience, male gets into mucky bath – pathetic
- Show impatience in talk about politician with silly hat, I bet
- I bet that potential winner in front is raring to go
- Top sportsman with time in heat set off scrap to show impatience
Buddy explains!
The straight part
We know that "raring to go" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case raring to go = champ at the bit.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.