Tell tale activity (7)
I believe the answer is:
archery
'tell tale activity' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for archery that I've seen before include "Arrow-shooting" , "The sport of shooting arrows with a bow" , "Sport of the bowman" , "The sport of bowmen" , "Target sport - Olympic event in from 1900-08, in 1920 and since 1972" .)