Clocklike device (5)
I believe the answer is:
timer
'clocklike device' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for timer that I've seen before include "one of 14 [CUCKOO CLOCKS]" , "Preset mechanisation to activate a device" , "Remit for, say, measuring device - or the measurer (5)" , "Watch, for example" , "Clock or watch" .)