The most common and most likely answer to this crossword clue is the 5 letter word DECAF
I've seen this crossword clue in The Sunday Telegraph
D
E
C
A
F
More clues leading to the result DECAF
- Drink available from inside cafe
- Accepted being sent back to find healthier hot drink?
- Non-alcoholic drink looked at after recovery?
- Not hearing about cold drink
- Met over coffee
- On reflection, resisted making coffee
- Dealt with returning coffee with something lacking
- Met up for coffee
- Revolutionary looked at something less stimulating?
- Met over a drink
Buddy explains!

The straight part
We know that "missing kick in cup?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case missing kick in cup? = decaf.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 DECAF mean?
DECAF noun- A decaffeinated coffee, tea, or soft drink.