Strangely frightening in middle of Great Lake (5)
I believe the answer is:
eerie
'strangely frightening' is the definition.
(I've seen this before)
'middle of great lake' is the wordplay.
'middle of' means to look at the middle letters.
'lake' becomes 'erie' (Lake Erie is one of the Canadian/US 'Great Lakes').
The middle letter of 'great' is 'e'.
'e'+'erie'='EERIE'
'in' acts as a link.
(Other definitions for eerie that I've seen before include "Scary, weird" , "Strange, frightening" , "Spooky, weird" , "Mysterious" , "Spectral" .)