No rays from the sun on St Tropez water? That's new (7)
I believe the answer is:
nouveau
'new' is the definition.
(I've seen this before)
'no rays from the sun on st tropez water?' is the wordplay.
I cannot quite see how this works, but
'no' could be 'o' (O resembles 0) and 'o' is present in the answer.
'water?' could be 'eau' (I have seen 'French water ' mean 'eau' so perhaps 'water' could also mean 'eau') and 'eau' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for nouveau that I've seen before include "It's new in France" , "A recently rich person, . . . . . . . riche" , "New to the French" , "like young Beaujolais" , "latest" .)