Exercise with body part raised (4,2)
I believe the answer is:
warm up
'exercise' is the definition.
(I have seen 'Preparatory exercise' mean 'warm-up' so perhaps 'exercise' could also mean 'warm-up')
'with body part raised' is the wordplay.
'with' becomes 'w' (abbreviation).
'body part' becomes 'arm' (arm is a kind of body part**).
'raised' becomes 'up' ('up' can be similar in meaning to 'raised').
'w'+'arm'+'up'='WARM-UP'
(Other definitions for warm up that I've seen before include "heat" , "race preparation" , "Rehearse" , "Practise" , "Athletes do it" .)