The most common and most likely answer to this crossword clue is the 10 letter word ASSISTANCE
I've seen this crossword clue in Independent
A
S
S
I
S
T
A
N
C
E
More clues leading to the result ASSISTANCE
- A hand in seas cast adrift
- If knackered, siestas can help
- Son is in a position to give help
- First to replace middle of song in poet, Owen’s sort of rhyme gets help
- Help idiot start to improve posture
- Help fool individual with attitude
- Support point of view taken on animal insurance at the outset
- Head of state is in a position to get help
- Help moving cases isn’t available, initially
- Help a relative into position
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 = assistance.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 ASSISTANCE mean?
ASSISTANCE noun- Aid; help; the act or result of assisting.