Famous person, judge, to paint the town red (9)
I believe the answer is:
celebrate
'paint the town red' is the definition.
(thesaurus)
'famous person judge' is the wordplay.
'famous person' becomes 'celeb' (I've seen this before).
'judge' becomes 'rate' (rating is a kind of judging).
'celeb'+'rate'='CELEBRATE'
'to' is the link.
(Other definitions for celebrate that I've seen before include "Stage a special festivity" , "have a good time" , "Rejoice or commemorate" , "Have festivity for special day or occasion" , "Be festive" .)