The most common and most likely answer to this crossword clue is the 9 plus 5 letter word COMMITTEE STAGE
I've seen this crossword clue in The Times
C
O
M
M
I
T
T
E
E
S
T
A
G
E
More clues leading to the result COMMITTEE STAGE
Buddy explains!
The straight part
We know that "Bill will go through it" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bill will go through it = committee stage.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.