Certain philosophers revolutionised science with big apple (6)
I believe the answer is:
cynics
'certain philosophers' is the definition.
(the cynics were ancient Greek philosophers)
'revolutionised science with big apple' is the wordplay.
'revolutionised' is a reversal indicator.
'science' becomes 'sci' (eg in 'poli sci' for political science).
'with' is a charade indicator (letters next to each other).
'big apple' becomes 'nyc' (the Big Apple is a nickname for New York City).
'sci'+'nyc'='scinyc'
'scinyc' backwards is 'CYNICS'.
(Other definitions for cynics that I've seen before include "Philosophers" , "They're said to know the price of everything and the value of nothing" , "Disillusioned people given to disbelieving" , "They take a pessimistic view of human goodness" , "They are hard to convince, sceptical people" .)