In money, I have a spur (9)
I believe the answer is:
incentive
'a spur' is the definition.
(thesaurus)
'in money i have' is the wordplay.
'money' becomes 'cent' (I've seen this before).
'i have' becomes 'ive'.
'in'+'cent'+'ive'='INCENTIVE'
(Other definitions for incentive that I've seen before include "Inducement" , "Payment to improve" , "Motivating payment" , "Stimulus" , "carrot" .)