Lifting couch is exercise (3-2)
I believe the answer is:
sit-up
'exercise' is the definition.
(I have seen 'Physical exercise ' mean 'sit-up' so perhaps 'exercise' could also mean 'sit-up')
'lifting couch is' is the wordplay.
'lifting' shows that the letters should be reversed in order.
'couch' becomes 'put' ('put' can be a synonym of 'couch').
'put'+'is'='putis'
'putis' reversed gives 'SIT UP'.
(Other definitions for sit-up that I've seen before include "Exercise designed to strengthen stomach muscles" , "Physical exercise" , "Exercise done on the floor" .)