Crossword Genius

Relaxed next to an evil spirit (5)

Ross

I believe the answer is:

'evil spirit' is the definition.
(thesaurus)

'relaxed next to an' is the wordplay.
'relaxed' becomes 'sat' (sitting is a type of relaxing).
'next to' says to put letters next to each other.
'sat'+'an'='SATAN'

(Other definitions for satan that I've seen before include "Old Nick, Lucifer or Beelzebub", "arch-fiend", "Fallen archangel", "Fiend", "Diabolical figure".)

I've seen this clue in Mirror.