Upgrade hospital in Cornish town without parking zone (7)
I believe the answer is:
enhance
'upgrade' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for enhance that I've seen before include "Improve the value of (something)" , "Improve, add to attractiveness of" , "'Improve, augment (7)'" , "To improve matters" , "Improve, make more attractive" .)