Uncertain flying (2,3,3)
I believe the answer is:
in the air
This clue is a double definition.
'uncertain' is the first definition.
(I've seen this before)
'flying' is the second definition.
(I've seen this before)
(Other definitions for in the air that I've seen before include "when travelling by plane" , "a possibility" , "Unsettled" , "Where clouds are" , "Undecided; current" .)