No fewer than fifty each in a test (not English) (2,5)
I believe the answer is:
at least
'no fewer than' is the definition.
('at least' can be a synonym of 'no fewer than')
'fifty each in a test not english' is the wordplay.
'fifty' becomes 'l' ('L' can be a synonym of 'fifty').
'each' becomes 'ea'.
'in' means one lot of letters goes inside another.
'not' indicates named letters should be taken away.
'english' becomes 'e' (abbreviation).
'test' with 'e' taken away is 'tst'.
'l'+'ea'='lea'
'a'+'tst'='atst'
'lea' put within 'atst' is 'AT LEAST'.
(Other definitions for at least that I've seen before include "Anyway" , "Eat salt (anag) - if nothing else" , "As a minimum" , "No less than" , "'If nothing else (2,5)'" .)