One showing no haste to get treatment? (7)
I believe the answer is:
patient
'one showing no haste to get treatment?' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'one' is the wordplay.
I cannot quite see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is found within the answer.
The remaining letters 'patent' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for patient that I've seen before include "Willing to wait" , "Cool" , "Uncomplaining; invalid" , "one of interest to medics?" , "One being treated" .)