Fly solo (2,2,5)
I believe the answer is:
go it alone
'fly solo' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for go it alone that I've seen before include "Take something on on one's own" , "Take something on, eschewing any help" , "Act independently" , "act without help" , "Proceed without the help of others" .)