1) Castanet 2) Remote 1) Remote control 2) User, at times 
A toy noisemaker used by animal trainers as an event marker to mark a desired performance or response.
A clicker is any device that makes a clicking sound, usually when deliberately activated by its user. They usually consist of a piece of thin metal or plastic held in a casing so that the metal is slightly torqued; depressing one end of the metal causes it to pop out of alignment and releasing it causes it to pop back into alignment, each time mak...
• (n.) One who stands before a shop door to invite people to buy. • (n.) One who as has charge of the work of a companionship.
Click'er noun 1. One who stands before a shop door to invite people to buy. [ Low, Eng.] 2. (Print.) One who as has charge of the work of a companionship. 
Clicker is slang for marijuana dipped in formaldehyde and smoked.
Equipment which is used for pointing out the optimal draw length of the shooter.
A device attached to the bow which gives an audible warning when the required draw length has been reached. The 'click' to often used by archers as a signal to release.
Small strip of metal mounted on the sight window in front of the arrow rest giving precise indication of full draw by snapping off the arrow point with an audible “click”.
someone or something that clicks. · See(def. 2).
Metal or plastic device. Produces audible click when arrow is at full draw.