The most common and most likely answer to this crossword clue is the 7 letter word BRACING
I've seen this crossword clue in The Daily Telegraph
B
R
A
C
I
N
G
Buddy explains!
The straight part
We know that "Supporting" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case supporting = bracing.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 BRACING mean?
BRACING verb- To prepare for something bad, such as an impact or blow.
- To place in a position for resisting pressure; to hold firmly.
- To swing round the yards of a square rigged ship, using braces, to present a more efficient sail surface to the direction of the wind.
- To stop someone for questioning, usually said of police.
- To confront with questions, demands or requests.
- To furnish with braces; to support; to prop.
- To draw tight; to tighten; to put in a state of tension; to strain; to strengthen.
- To bind or tie closely; to fasten tightly.
- That which braces.
- A brace.
- A form of the military attention stance.
- Invigorating or stimulating.