Incentive to have money (4)
I believe the answer is:
cent
'money' is the definition.
(eg denomination of dollars)
'incentive to have' is the wordplay.
'to have' indicates the answer is hidden within the clue.
'CENT' is hidden in the letters of 'incentive'.
(Other definitions for cent that I've seen before include "Small monetary unit" , "One-hundredth of the basic monetary unit" , "One hundredth of a euro" , "Fractional monetary unit" , "One hundreth of a dollar" .)