The most common and most likely answer to this crossword clue is the 5 letter word PORES
I've seen this crossword clue in Financial Times
P
O
R
E
S
Buddy explains!

The straight part
We know that "holes" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case holes = pores.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 PORES mean?
PORES noun- A tiny opening in the skin.
- By extension any small opening or interstice, especially one of many, or one allowing the passage of a fluid.
- To study meticulously; to go over again and again.
- To meditate or reflect in a steady way.