Under pressure, sweets sent back (8)
I believe the answer is:
stressed
'under pressure' is the definition.
(I've seen this before)
'sweets sent back' is the wordplay.
'sweets' becomes 'desserts' ('dessert' can be a synonym of 'sweet').
'sent back' is a reversal indicator.
'desserts' written backwards gives 'STRESSED'.
(Other definitions for stressed that I've seen before include "Subjected to strain or emphasised." , "overwrought" , "Pressurised, strained" , "Feeling tension" , "anxious" .)