Hidden a crane away (6)
I believe the answer is:
arcane
'hidden' is the definition.
(thesaurus)
'a crane away' is the wordplay.
'away' is an anagram indicator.
'crane' is an anagram of 'rcane'.
'a'+'rcane'='ARCANE'
(Other definitions for arcane that I've seen before include "Requiring secret or mysterious knowledge" , "Recondite" , "Mysterious, secret or obscure" , "Esoteric, mysterious" , "Abstruse, mysterious" .)