The most common and most likely answer to this crossword clue is the 4 letter word HUCK
I've seen this crossword clue in The Guardian
H
U
C
K
Buddy explains!
The straight part
We know that "Finn" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case finn = huck.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 HUCK mean?
HUCK noun- (Ultimate Frisbee) A long throw, generally at least half a field in length.
- A drop or jump off a cliff or cornice.
- To throw or chuck.
- To throw oneself off a large jump or drop.
- To throw one's body in the air, possibly in a way that is ungraceful or lacks skill.
- (Ultimate Frisbee) To throw a frisbee a long distance.
- (Ultimate Frisbee) To make a long throw with the frisbee; to start a point by making such a throw.
- (mountain biking) To attempt a particularly big jump or drop, often haphazardly.
- (mountain biking) To make a maneuver in a clumsy or poorly planned way.
- (whitewater kayaking) To paddle off a waterfall or to boof a big drop.
- A person's hip.
- To haggle in trading.