Maintain, preserve (4,2)
I believe the answer is:
keep up
I believe this clue is a double definition.
'maintain' is the first definition.
(I know that maintain can be written as keep up)
'preserve' is the second definition.
(I know that preserve can be written as keep up)
(Other definitions for keep up that I've seen before include "Stay in contention" , "Maintain pace with, don't lag behind" , "Continue to be in touch (with)" , "Stick with" , "Stay with the pace, don't fall behind" .)