The most common and most likely answer to this crossword clue is the 4 plus 6 letter word GREY MATTER
I've seen this crossword clue in The Daily Telegraph
G
R
E
Y
M
A
T
T
E
R
More clues leading to the result GREY MATTER
- Brains you need for such an ill-defined issue?
- Sign of maturity? Comparatively less lustrous nous
- Anatomist speaking on less shiny part of head
- Ill-defined affair that indicates intelligence
- Dull affair that shows intelligence
- Aristocratic woman with count shows common sense
- Intelligence is a boring topic
- Common sense of former PM facing question
Buddy explains!
The straight part
We know that "Common sense" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case common sense = grey matter.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.