Nice man? (8)
I believe the answer is:
monsieur
'nice man?' is the definition.
(equivalent to mister in French - eg in Nice)
'man?' is the wordplay.
I cannot really see how this works, but
'man?' could be 'si' and 'si' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for monsieur that I've seen before include "French man" , "French male title" , "French gentleman" , "Frenchman's title" , "Frenchman" .)