Obsession (5)
'obsession' is the definition.
(I've seen this in other clues)
This is the entire clue.
(Other definitions for thing that I've seen before include "A creature" , "Obsession" , "Individual unit" , "Individual object" , "See 1" .)
'obsession' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for mania that I've seen before include "Obsessional enthusiasm" , "thing" , "Excessive enthusiasm" , "fixation" , "Madness - craze" .)