Tiny period (6)
I believe the answer is:
minute
This clue is a double definition.
'tiny' is the first definition.
(minute can mean small)
'period' is the second definition.
(minute is a kind of period)
(Other definitions for minute that I've seen before include "official memorandum" , "It's not very long" , "Occupying very little space" , "Lilliputian" , "Brief jotting" .)