Legendary swimmer left Scots horsemen at sea around noon (4,4,7)
I believe the answer is:
loch ness monster
'legendary swimmer' is the definition.
'Loch Ness monster' can be an answer for 'swimmer' (thesaurus). I'm not sure about the 'legendary' bit.
'left scots horsemen at sea around noon' is the wordplay.
'left' becomes 'l' (common abbreviation).
'at sea' indicates anagramming the letters.
'around' means one lot of letters goes inside another.
'noon' becomes 'n'.
'l'+'scots'+'horsemen'='lscotshorsemen'
'lscotshorsemen' is an anagram of 'lochnessmoster'.
'lochnessmoster' enclosing 'n' is 'LOCH NESS MONSTER'.
Can you help me to learn more?
(Other definitions for loch ness monster that I've seen before include "chimera?" , "Fabulous creature" , "Scots apparition" , "Caledonian enigma" , "Legendary Scottish apparition" .)