The struggle to get ahead (3,4)
I believe the answer is:
rat race
'the struggle to get ahead' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for rat race that I've seen before include "The struggle for survival" , "Competition for power" , "Competitive way of life" , "Scramble to succeed" , "Life seen as competition" .)