Obligations heartless aristocrats create (4)
I believe the answer is:
dues
'aristocrats create' is the definition.
I can't tell whether this defines the answer.
'obligations heartless' is the wordplay.
'obligations' becomes 'duties' ('duty' can be a synonym of 'obligation').
'heartless' says to hollow out the word (remove centre letters).
'duties' with its middle removed is 'DUES'.
Can you help me to learn more?
(Other definitions for dues that I've seen before include "subs" , "Payments made for upkeep of church" , "Subscription to a club or society" , "Membership fees" .)