Up in the sky (6)
I believe the answer is:
aerial
'up in the sky' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for aerial that I've seen before include "Radio waves receiver" , "Device to send and receive radio signals" , "Antenna for capturing radio or TV signals" , "Rod or antenna for receiving signals" , "Signal receiver" .)