Oddly, cool gin is extremely acidic unlike this, more expensive drink (6)
I believe the answer is:
cognac
'drink' is the definition.
(Cognac is an example)
'oddly cool gin is extremely acidic' is the wordplay.
'oddly' indicates alternate letters (letters in the odd-numbered positions are used).
'is extremely' means to remove the middle letters (only the extremes of the word are used).
'acidic' with its middle removed is 'ac'.
'cool'+'gin'='coolgin'
The alternating letters of 'coolgin' are 'cogn'.
'cogn'+'ac'='COGNAC'
'unlike this more expensive' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for cognac that I've seen before include "French town - French brandy" , "Brandy of the French Charente" , "High quality brandy" , "(French district famed for) fine brandy" , "warmer" .)