Slimmed down (7)
I believe the answer is:
reduced
'slimmed down' is the definition.
('reduce' can be a synonym of 'slim down')
This is all the clue.
(Other definitions for reduced that I've seen before include "Lowered in price" , "Shortened" , "Got rid of some bodily weight" , "Lessened" , "Made less in size etc" .)