Limits certain stars (10)
I believe the answer is:
boundaries
'limits' is the definition.
('boundary' can be a synonym of 'limit')
'certain stars' is the wordplay.
'certain' becomes 'bound' (as in the phrase 'it's bound to be').
'stars' becomes 'Aries' (constellation).
'bound'+'aries'='BOUNDARIES'
(Other definitions for boundaries that I've seen before include "Limits" , "Borders" .)