The most common and most likely answer to this crossword clue is the 5 letter word OCTAL
O
C
T
A
L
More clues leading to the result OCTAL
- Centrally allocated in pieces of eight
- Coat left in pieces – of eight!
- Month to go over nearly everything to do with numbering system
- Base level at colder region to the West
- Concoct algorithm partly relating to base-8 number system
- Old corsair that's amassed Liberians' first pieces of eight
- Using smaller base: some flat, cottage retreats
- Based on eight-ounce coffees, teas, and lattes, for starters
Buddy explains!

The straight part
We know that "to do with numbering system" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case to do with numbering system = octal.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 OCTAL mean?
OCTAL noun- The number system that uses the eight digits 0, 1, 2, 3, 4, 5, 6, 7.
- A digit or value in the octal number system.
- Concerning numbers expressed in octal or mathematical calculations performed using octal.