Ticker
/ˈtɪkər/
Definition 1 of 3
Pro Tip 1/2Sound Association
Relate 'ticker' to the sound of ticking to remember its connection to timekeeping devices. 
The constant ticking from the grandfather clock made him think of its ticker.
Pro Tip 2/2Physical Object
Remember, 'ticker' often refers to an actual object, like a clock or watch. 
The teacher asked for complete silence and all you could hear was the wall clock's ticker.