The Little Mermaid (5)
I believe the answer is:
'the little mermaid' is the definition.
(main character from Disney's The Little Mermaid)
This is all the clue.
(Other definitions for ariel that I've seen before include "Fairy in "The Tempest"" , "spirit of Shakespeare" , "Sprite in The Tempest" , "Prospero's spirit (Tempest)" , "fairy sign" .)