The most common and most likely answer to this crossword clue is the 6 letter word CRANKS
I've seen this crossword clue in The Daily Telegraph
C
R
A
N
K
S
Buddy explains!
The straight part
We know that "obsessive folk" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case obsessive folk = cranks.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 CRANKS mean?
CRANKS noun- A bent piece of an axle or shaft, or an attached arm perpendicular, or nearly so, to the end of a shaft or wheel, used to impart a rotation to a wheel or other mechanical device; also used to change circular into reciprocating motion, or reciprocating into circular motion.
- The act of converting power into motion, by turning a crankshaft.
- Any bend, turn, or winding, as of a passage.
- An ill-tempered or nasty person.
- A twist or turn of the mind; caprice; whim;
- A fit of temper or passion.
- (dated in US) A person who is considered strange or odd by others. They may behave in unconventional ways.
- (1800s) A baseball fan.
- An advocate of a pseudoscience movement.
- A twist or turn in speech; word play consisting in a change of the form or meaning of a word.
- A sick person; an invalid.
- A penis.
- To turn by means of a crank.
- To turn a crank.
- (of a crank or similar) To turn.
- To cause to spin via other means, as though turned by a crank.
- To act in a cranky manner; to behave unreasonably and irritably, especially through complaining.
- To be running at a high level of output or effort.
- To run with a winding course; to double; to crook; to wind and turn.
- A highly addictive phenethylamine stimulant drug, similar to cocaine. Its systematic (IUPAC) name is (S)-N-methyl-1-phenylpropan-2-amine.