The most common and most likely answer to this crossword clue is the 9 letter word ITINERATE
I
T
I
N
E
R
A
T
E
Buddy explains!
The straight part
We know that "What nomads do" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case what nomads do = itinerate.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 ITINERATE mean?
ITINERATE verb- To travel from place to place, especially to preach or lecture.