Dainty, a little thin, I flew upward (5)
I believe the answer is:
elfin
'dainty' is the definition.
(I've seen this before)
'a little thin i flew upward' is the wordplay.
'a little' indicates the answer is hidden within the clue.
'upward' says the letters should be written backwards.
'nifle' can be found hidden inside 'thin i flew'.
'nifle' backwards is 'ELFIN'.
(Other definitions for elfin that I've seen before include "Little, charming and naughty" , "Describing Santa's helpers" , "Fairy-like" , "Small; impish" , "Dainty" .)