The most common and most likely answer to this crossword clue is the 8 letter word COALMINE
I've seen this crossword clue in The Daily Telegraph
C
O
A
L
M
I
N
E
Buddy explains!

The straight part
We know that "pit" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pit = coalmine.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 COALMINE mean?
COALMINE noun- A mine from which coal ore or coal minerals are mined.