Strained sweet courses knocked back (8)
I believe the answer is:
stressed
'strained' is the definition.
('stress' can be a synonym of 'strain')
'sweet courses knocked back' is the wordplay.
'sweet courses' becomes 'desserts' (I've seen this before).
'knocked back' says the letters should be written backwards.
'desserts' written backwards gives 'STRESSED'.
(Other definitions for stressed that I've seen before include "Hassled, under pressure" , "Pressurised, strained" , "Accented, underlined" , "Under great strain" , "overwrought" .)