Weird echo on the lake (5)
I believe the answer is:
eerie
'weird' is the definition.
(both can mean strange or unsettling)
'echo on the lake' is the wordplay.
'echo' becomes 'e' (phonetic alphabet: alpha, bravo, charlie etc.).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'the lake' becomes 'erie' (Lake Erie is one of the Canadian/US 'Great Lakes').
'e'+'erie'='EERIE'
(Other definitions for eerie that I've seen before include "Strange and disturbing" , "Awesome" , "Bloodcurdling" , "Strange, frightening" , "Unnatural" .)