Media finished exercise (5-2)
I believe the answer is:
press-up
'exercise' is the definition.
(I know that press-up is a type of arm exercise)
'media finished' is the wordplay.
'media' becomes 'press' (the press is part of the media).
'finished' becomes 'up' (eg 'time's up' means the time is finished).
'press'+'up'='PRESS-UP'
(Other definitions for press-up that I've seen before include "Face-to-the-floor exercise" , "Gymnastic floor exercise" , "Keep-fit exercise" , "Arm exercise while lying face down" , "PE exercise" .)