If nothing else (2,5)
I believe the answer is:
at least
'if nothing else' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for at least that I've seen before include "Anyway" , "'If nothing else (2,5)'" , "Eat salt (anag) - if nothing else" , "No less than" , "As a minimum" .)