The most common and most likely answer to this crossword clue is the 7 letter word BACKING
I've seen this crossword clue in The Daily Telegraph
B
A
C
K
I
N
G
More clues leading to the result BACKING
- Support Britain wanting rid of leader
- Support going counterclockwise
- Supporting vehicle turning up ahead of ruler
- Support very hot — Conservative gets in
- Trams will become smart after this support
- Supporting, though not coming forward
- Cher’s opening amid torrid musical accompaniment
- Withdrawing support?
- Support in reverse
- Gambling on promotion
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 = backing.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 BACKING mean?
BACKING verb- To go in the reverse direction.
- To support.
- (of the wind) To change direction contrary to the normal pattern; that is, to shift anticlockwise in the northern hemisphere, or clockwise in the southern hemisphere.
- (of a square sail) To brace the yards so that the wind presses on the front of the sail, to slow the ship.
- (of an anchor) To lay out a second, smaller anchor to provide additional holding power.
- (of a hunting dog) To stand still behind another dog which has pointed.
- To push or force backwards.
- To get upon the back of; to mount.
- To place or seat upon the back.
- To make a back for; to furnish with a back.
- To adjoin behind; to be at the back of.
- To write upon the back of, possibly as an endorsement.
- (of a justice of the peace) To sign or endorse (a warrant, issued in another county, to apprehend an offender).
- To row backward with (oars).
- Support, especially financial.
- A liner or other material added behind or underneath.
- A backdrop.
- Musicians and vocalists who support the main performer.
- The mounting of a horse or other animal.
- The action of putting something back; a switching into reverse.
- Providing support for the main performer.