Stress rises after diet disallows occasional sweet courses (8)
I believe the answer is:
desserts
'sweet courses' is the definition.
(I've seen this before)
'stress rises after diet' is the wordplay.
'rises' says the letters should be written in reverse.
'after' says to put letters next to each other.
'diet' becomes 'de' (I can't justify this - if you can you should believe this answer much more).
'stress' back-to-front is 'sserts'.
'sserts' put after 'de' is 'DESSERTS'.
'disallows occasional' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for desserts that I've seen before include "Sweets" , "That may be cobblers" , "Sweet courses of meal" , "Final courses" , "fools, perhaps?" .)