The most common and most likely answer to this crossword clue is the 8 letter word ABACUSES
I've seen this crossword clue in The Times
A
B
A
C
U
S
E
S
More clues leading to the result ABACUSES
Buddy explains!
The straight part
We know that "you can count on them" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case you can count on them = abacuses.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 ABACUSES mean?
ABACUSES noun- A table or tray scattered with sand which was used for calculating or drawing.
- A device used for performing arithmetical calculations; a table on which loose counters are placed, or (more commonly) an instrument with beads sliding on rods, or counters in grooves, with one row of beads or counters representing units, the next tens, etc.
- The uppermost portion of the capital of a column immediately under the architrave, in some cases a flat oblong or square slab, in others more decorated.
- A board, tray, or table, divided into perforated compartments for holding bottles, cups, or the like; a kind of buffet, cupboard, or sideboard.