Fairy queen admitted to malice (6)
I believe the answer is:
sprite
'fairy' is the definition.
('sprite' can be a synonym of 'fairy')
'queen admitted to malice' is the wordplay.
'queen' becomes 'r' (r is abbreviation regina. e.g. in ER ).
'admitted to' is an insertion indicator.
'malice' becomes 'spite' (spite is a kind of malice).
'r' going inside 'spite' is 'SPRITE'.
(Other definitions for sprite that I've seen before include "Supernatural being" , "Dainty type" , "Elf, fairy" , "Small, playful fairy" , "Naiad" .)