Course isn't for the casual - head off without charge (7)
I believe the answer is:
aintree
'course isn't' is the definition.
'aintree' can be an answer for 'course' (I've seen this before). I'm not certain of the 'isn't' bit.
'casual head off without charge' is the wordplay.
'casual' becomes 'aint' (I am not sure about this - if you are sure you should believe this answer much more).
'head off' means to remove the first letter.
'without charge' becomes 'free' (sold at no cost).
'free' with its initial letter taken off is 'ree'.
'aint'+'ree'='AINTREE'
'for the' is the link.
Can you help me to learn more?
(Other definitions for aintree that I've seen before include "6 National course" , "place for horse racing" , "Venue of the Grand National race" , "Trainee in Grand National venue" , "Liverpool racecourse" .)