The most common and most likely answer to this crossword clue is the 6 letter word SCALAR
I've seen this crossword clue in The Daily Telegraph
S
C
A
L
A
R
Buddy explains!

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 SCALAR mean?
SCALAR noun- A quantity that has magnitude but not direction; compare vector
- An amplifier whose output is a constant multiple of its input
- Having magnitude but not direction
- Consisting of a single value (e.g. integer or string) rather than multiple values (e.g. array)
- Of, or relating to scale
- Of or pertaining to a musical scale.