Frog. It only has four letters, removing the “r” leaves fog, which makes it hard to see. Changing the “r” to an “l” makes flog, a punishment I hope you’ve never experienced. Flog backwards is golf, a game some would call a punishment when you keep swinging away at the ball yet it remains perched on its little white tower of terror while the other golfers impatiently wait for you to tee off.
The riddle refers to a variety of meanings of the word fine.
Feeling normal refers to when you feel fine.
Extremely thin refers to a fine thread.
A punishment refers to being charged a fee.
The one who wins refers to an athlete who is physically trained and hardened close to the limit of efficiency.
Free from impurity refers to measuring the fineness of precious metals.
A keen edge refers to a knife with a fine edge.
Refined refers to fine manners or elegance.
Amazingly, this actually happened. The parents died in a crash crash and their parents fought for the rights to the four frozen embryos left by their late children. After a surrogate pregnancy, the baby was born with DNA matching their deceased parents.