The most common and most likely answer to this crossword clue is the 7 plus 6 letter word DECIMAL SYSTEM
D
E
C
I
M
A
L
S
Y
S
T
E
M
More clues leading to the result DECIMAL SYSTEM
Buddy explains!
The straight part
We know that "scheme for two-handed working?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case scheme for two-handed working? = decimal system.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.