### Clue: We join "stationary" flight, regardless (7)
### Answer: HOWEVER 
 ### Explanation: We join "stationary" flight, regardless (7) 
HO(WE)VER
 
I haven't come across "join" used in this way before, but as far as I can work out, it is being used in the sense of "to go to and remain within" such as to "join a club"?