Tropical island crop (9)
I believe the answer is:
capricorn
'tropical island crop' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'island crop' is the wordplay.
'island' becomes 'Capri' (Italian island).
'crop' becomes 'corn' (a farmer's crop of corn).
'capri'+'corn'='CAPRICORN'
Can you help me to learn more?
(Other definitions for capricorn that I've seen before include "Tropic - Zodiac sign" , "Constellation known as The Goat" , "7 [SIGN OF THE ZODIAC]" , "It's a Tropic, and the Sign of the Goat" , "Goat star sign" .)