Infamous collective denial enthrals hunter endlessly (9)
I believe the answer is:
notorious
'infamous' is the definition.
('notorious' can be a synonym of 'infamous')
'collective denial enthrals hunter endlessly' is the wordplay.
'collective denial' becomes 'notus' (I can't explain this - if you can you should give a lot more credence to this answer).
'enthrals' means one lot of letters goes inside another.
'hunter' becomes 'orion' (constellation).
'endlessly' means to remove the last letter.
'orion' with its final letter removed is 'orio'.
'notus' going around 'orio' is 'NOTORIOUS'.
(Other definitions for notorious that I've seen before include "Infamous" , "having a terrible reputation?" , "Disreputable - 1946 Hitchcock classic" , "Famous for misdeeds" , "Scandalous" .)