European lake is creepy (5)
I believe the answer is:
eerie
'creepy' is the definition.
(eerie can mean strange or creepy)
'european lake' is the wordplay.
'european' becomes 'E' (abbreviation e.g. EU).
'lake' becomes 'erie' (Lake Erie is one of the Canadian/US 'Great Lakes').
'e'+'erie'='EERIE'
'is' acts as a link.
(Other definitions for eerie that I've seen before include "Spooky, supernatural" , "spine-chilling" , "Strange, unusual" , "Unnatural" , "Spooky, creepy" .)