Cruel way to make money (5)
I believe the answer is:
lucre
'money' is the definition.
(lucre is a kind of money)
'cruel way' is the wordplay.
'way' indicates an anagram (another way of arranging the letters).
'cruel' with letters rearranged gives 'LUCRE'.
'to make' is the link.
(Other definitions for lucre that I've seen before include "Possession of the rich" , "ill-gotten gains" , "Money (especially when gained dishonourably)" , "There's money" , "Cruel kind of money, may be filthy" .)