Cancun's peninsula (7)
I believe the answer is:
yucatan
'cancun's peninsula' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for yucatan that I've seen before include "Mexican peninsula where Mayas lived" , "N. Mexican peninsula" , "part of Mexico" , "Alcoholic drink" , "Mayan area of Mexico" .)