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 certain of the rest of the definition.
'an hour to change course?' is the wordplay.
'to change' is an anagram indicator.
'course?' becomes 'n' ().
'hour' with letters rearranged gives 'huro'.
'huro'+'n'='HURON'
'it's' is the 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" .)