Cold drink in summery Spain is sweet (9)
I believe the answer is:
chocolate
'is sweet' is the definition.
(thesaurus)
'cold drink in summery' is the wordplay.
'cold' becomes 'c' (eg on taps).
'drink' becomes 'cola' (cola is a kind of drink).
'in' indicates putting letters inside.
'summery' becomes 'hote' (I can't explain this - if you can you should give a lot more credence to this answer).
'cola' going inside 'hote' is 'hocolate'.
'c'+'hocolate'='CHOCOLATE'
'spain' acts as a link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for chocolate that I've seen before include "The tasty treat could turn out to be a cool cheat" , "The tasty treat turns out to be a cool cheat" , "Cacao product" , "Coca hotel is a treat" , "Sweet made with cacao beans" .)