The most common and most likely answer to this crossword clue is the 5 plus 7 letter word TROGS (GROTS)
T
R
O
G
S
(
G
R
O
T
S
)
Buddy explains!
The straight part
We know that "Caves" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case caves = trogs (grots).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.