Reverse vehicle into space initially unavailable: good advice? (6)
I believe the answer is:
oracle
'unavailable good advice?' is the definition.
'oracle' can be an answer for 'advice?' (thesaurus). I am not sure about the 'unavailable good' bit.
'reverse vehicle into space initially' is the wordplay.
'reverse' says the letters should be written in reverse.
'vehicle' becomes 'car' (car is a kind of vehicle).
'into' is an insertion indicator.
'space initially' becomes 'elo' (I can't justify this - if you can you should give a lot more credence to this answer).
'car' placed inside 'elo' is 'elcaro'.
'elcaro' written backwards gives 'ORACLE'.
Can you help me to learn more?
(Other definitions for oracle that I've seen before include "One believed to give divinely-inspired answers" , "Place where ancient Greeks consulted a god or prophet" , "Expert" , "Authoritative statement" , "source of revelation?" .)