Out for number one (7)
I believe the answer is:
selfish
'out for number one' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for selfish that I've seen before include "Self-seeking" , "Concerned only with oneself" , "Egocentric - greedy" , "Concerned only with one's personal welfare" , "Concerned chiefly with one's own interests" .)