Fine swimmers showing a bad result when they lose their head (7)
I believe the answer is:
turtles
'fine swimmers' is the definition.
'turtles' can be an answer for 'swimmers' (turtles swim). I am not certain of the 'fine' bit.
'a bad result when they lose their head' is the wordplay.
I cannot quite see how this works, but
an anagram of 'result' is 'urtles' which is located in the answer.
A single letter 't' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'showing' is the link.
Can you help me to learn more?
(Other definitions for turtles that I've seen before include "Reptiles with bony shell and flipper-like limbs" , "Marine reptiles" , "Swimming reptiles" , "Let rust settle on sea-creatures" , "The reptiles are let rust" .)