Phantom hunter lay prepared (9)
I believe the answer is:
unearthly
'phantom' is the definition.
(thesaurus)
'hunter lay prepared' is the wordplay.
'prepared' is an anagram indicator.
'hunter'+'lay'='hunterlay'
'hunterlay' is an anagram of 'UNEARTHLY'.
(Other definitions for unearthly that I've seen before include "So unpleasantly early an hour" , "H G Wells's invaders appeared?" , "Preposterous" , "Sunny" , "Mysterious and disturbing" .)