The most common and most likely answer to this crossword clue is the 7 letter word MISTERS
M
I
S
T
E
R
S
Buddy explains!

The straight part
We know that "Fellows/moisteners" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fellows/moisteners = misters.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 MISTERS mean?
MISTERS noun- A title conferred on an adult male, usually when the name is unknown. Also used as a term of address, often by a parent to a young child.
- Someone's business or function; an occupation, employment, trade.
- A kind, type of.
- Need (of something).
- Necessity; the necessary time.
- A device that makes or sprays mist.