The most common and most likely answer to this crossword clue is the 7 letter word TECHNIC
I've seen this crossword clue in The Times
T
E
C
H
N
I
C
Buddy explains!
The straight part
We know that "MO in US" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case mo in us = technic.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 TECHNIC mean?
TECHNIC noun- The method of performance in any art; technique.
- (in the plural) Technical terms or objects; things pertaining to the practice of an art or science.
- (in the plural) The doctrine of arts in general; those branches of learning that relate to the arts.
- Technical