Nothing clear about seer (6)
I believe the answer is:
oracle
'seer' is the definition.
(thesaurus)
'nothing clear about' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'about' indicates an anagram.
'clear' with letters rearranged gives 'racle'.
'o'+'racle'='ORACLE'
(Other definitions for oracle that I've seen before include "Divinely-inspired prophecy" , "Where advice or prophecy was sought from the gods in ancient Greece" , "Fount of divine inspiration" , "Ancient Greek expounder of wisdom" , "Person regarded as source of knowledge, like old Greek prophet" .)