Count Gessler's opponent (4)

I believe the answer is:

tell

I'm a little stuck... Click here to teach me more about this clue!

'count' is the definition.
(I've seen this before)

I can't explain the remainder of the clue.

(Other definitions for tell that I've seen before include "Notify" , "Instruct" , "One who refused to accept tyranny" , "blow the whistle" , "... national hero" .)

I've seen this clue in The Globe and Mail.

Want a hint initially instead of a full solution? Install my app