21 down
Counter
when
a
god
denied
church
(6)
Counter when a god denied church (6)
hints
0
checks
0
hints
The definition is at the beginning of the clue.
How the clue works
Counter is your definition here, pointing to the counting device. Start with A, then add BACCHUS (a god) to get ABACCHUS, and "denied church" tells you to knock out CH from the middle, leaving ABACUS.