Belt of the heavens (6)
I believe the answer is:
zodiac
'belt of the heavens' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for zodiac that I've seen before include "Astronogical sky band with 12 parts" , "Astrological belt" , "Horoscope diagram" , "Astrological band of the sky with 12 signs" , "Diagram of astrological signs" .)