The most common and most likely answer to this crossword clue is the 7 letter word ABETTAL
I've seen this crossword clue in The Guardian
A
B
E
T
T
A
L
More clues leading to the result ABETTAL
- Helping discontented barista around coffee counter
- A black coffee sent over, supporting a tea leaf, perhaps?
- Sailor throwing up coffee gets encouragement
- Sailor bringing drink up as encouragement
- Support a black and white drink that’s knocked over
- Encouragement at table to get moving
- A form of tablet for assistance
- Encouraging con’s a gamble supported by endless white powder
- Coffee discontented barista knocked over, helping criminal
Buddy explains!

The straight part
We know that "Support" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case support = abettal.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.