Judges to be a variety of aster (5)
I believe the answer is:
rates
'judges' is the definition.
(rating is a kind of judging)
'a variety of aster' is the wordplay.
'a variety of' is an anagram indicator.
'aster' anagrammed gives 'RATES'.
'to be' is the link.
(Other definitions for rates that I've seen before include "Former local tax" , "Esteems, values" , "judges" , "Property-based source of local revenue" , "Taxes paid by businesses to local authority" .)