Mitre (anag.) (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
timer
(Other definitions for timer that I've seen before include "Watch, for example" , "one of 14 [CUCKOO CLOCKS]" , "Remit for, say, measuring device - or the measurer (5)" , "One may have the minutes" , "Pre-set switch" .)