Sure isn't deal taking 50% off hired car, for instance? (6)
I believe the answer is:
rental
'sure isn't deal' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe there's an association between them I don't understand?
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for rental that I've seen before include "money for landlord" , "Something paid for hire" , "Payment for hire" , "To do with a letting" , "Money paid for hire" .)