Prophet (6)
'prophet' is the definition.
(both can mean someone who tells the future)
This is the entire clue.
(Other definitions for seer that I've seen before include "Regard with respect" , "One having visions of the future" , "He forecasts" , "wise fellow" , "Wise person" .)
'prophet' is the definition.
(synonyms)
This is all the clue.
(Other definitions for oracle that I've seen before include "Augur - prediction" , "Infallible indication" , "Authority to be consulted" , "Wise words" , "Holy place where a god was believed to give advice and prophecy" .)