Go out and send back couple carrying cross (4)
I believe the answer is:
exit
'go out' is the definition.
('exit' can be a synonym of 'go out')
'send back couple carrying cross' is the wordplay.
'send back' says the letters should be written in reverse.
'couple' becomes 'tie' (I've seen this in other clues**).
'carrying' indicates putting letters inside.
'cross' becomes 'x'.
'tie' enclosing 'x' is 'tixe'.
'tixe' backwards is 'EXIT'.
'and' is the link.
(Other definitions for exit that I've seen before include "Means of egress" , "Departure of actor" , "Leave the stage" , "farewell!" , "Way to leave" .)