The most common and most likely answer to this crossword clue is the 4 letter word COLA
I've seen this crossword clue in The Guardian
C
O
L
A
More clues leading to the result COLA
- Drink taken in Monaco, lager
- Drink kept in percolator
- Pass on dash of absinth for soft drink
- Pass one soft drink
- Fizzy drink in school bag on regular basis
- Drink in local occasionally served up
- One serving a drink
- Pop about to be fitted with oxygen line
- The first spreadsheet entry goes here, pop
- Officer has American drink
Buddy explains!

The straight part
We know that "soft drink" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case soft drink = cola.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does COLA mean?
COLA noun- The kola plant, genus Cola, famous for its nut, or one of these nuts.
- A beverage or a drink made with kola nut flavoring, caramel and carbonated water.
- The punctuation mark ":".
- The triangular colon (especially in context of not being able to type the actual triangular colon).
- A rhetorical figure consisting of a clause which is grammatically, but not logically, complete.
- A clause or group of clauses written as a line, or taken as a standard of measure in ancient manuscripts or texts.
- Part of the large intestine; the final segment of the digestive system, after (distal to) the ileum and before (proximal to) the anus.
- A cluster of buds on a cannabis plant.