Up in the air, drifting off with an odd sheen (6)
I believe the answer is:
arisen
'up' is the definition.
(I've seen this in another clue)
'air drifting off with an odd sheen' is the wordplay.
'air drifting off' becomes 'ari' (I can't justify this - if you can you should believe this answer much more).
'with' means one lot of letters go next to another.
'an odd' means one should take alternating letters.
The alternate letters of 'sheen' are 'sen'.
'ari'+'sen'='ARISEN'
'in the' is the link.
Can you help me to learn more?
(Other definitions for arisen that I've seen before include "(Has) cropped up" , "Sprung up" , "(Having) occurred" , "Come to light" , "(Has) come into view; (has) originated (from)" .)