Though consulted, may make nothing clear (6)
I believe the answer is:
Here is my best explanation:
'though consulted may' is the definition.
I can't tell whether this definition defines the answer.
'make nothing clear' is the subsidiary indication.
'make' indicates anagramming the letters.
'nothing' becomes 'o' (looks like zero - 0).
'oclear' anagrammed gives 'oracle'.
(Other definitions for oracle that I've seen before include "She prophesised", "Authoritative statement", "sign of things to come", "voice", "Prophet or sage", "Infallible authority", "One forecasting", "source of revelation?", "Place where ancient Greeks consulted a god or prophet" and "Wise utterance".)