Part of the complexity is way out (4)
I believe the answer is:
exit
'way out' is the definition.
('exit' can be a synonym of 'way out')
'part of the complexity is' is the wordplay.
'part of' says the answer is hidden in the clue.
'EXIT' is hidden in the letters of 'complexity is'.
(Other definitions for exit that I've seen before include "Player's departure" , "Act of going out" , "Relinquish the lead" , "[DOOR] ?" , "Leave the stage" .)