Imagine a lot of discontented feelings around slump (8)
I believe the answer is:
envisage
'imagine' is the definition.
(I know that imagine can be written as envisage)
'a lot of discontented feelings around slump' is the wordplay.
'a lot of' means to remove the last letter (I've seen 'lots of' mean this (the majority of the word)).
'discontented feelings' becomes 'envies' (envy is a feeling of discontent).
'around' indicates putting letters inside.
'slump' becomes 'sag' (I've seen this before).
'envies' with its final letter taken off is 'envie'.
'envie' enclosing 'sag' is 'ENVISAGE'.
(Other definitions for envisage that I've seen before include "Imagine, foresee" , "Consider, contemplate" , "Conceive of, imagine" , "Mentally picture" , "Visualise, imagine" .)