Lake on which it's an hour to change course? (5)
I believe the answer is:
huron
'lake on which' is the definition.
'huron' can be an answer for 'lake' (I've seen this before). I am not sure about the remainder of the definition.
'an hour to change course?' is the wordplay.
'to change' indicates an anagram.
'course?' becomes 'n' ().
'hour' anagrammed gives 'huro'.
'huro'+'n'='HURON'
'it's' acts as a link.
Can you help me to learn more?
(Other definitions for huron that I've seen before include "Second largest of the Great Lakes" , "N. American lake" , "One of the Great Lakes of North America" , "Great Lake" .)