The most common and most likely answer to this crossword clue is the 9 letter word NUMERABLE
N
U
M
E
R
A
B
L
E
Buddy explains!
The straight part
We know that "Possibly within the capabilities of person who counts" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case possibly within the capabilities of person who counts = numerable.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 NUMERABLE mean?
NUMERABLE adjective- Able to be counted; countable.
- In one to one correspondence with the set of natural integers.
- Numerous