Keep-fit exercise (5-2)
I believe the answer is:
press-up
'keep-fit exercise' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for press-up that I've seen before include "Arm exercise while lying face down" , "Form of arm exercise" , "PE exercise" , "Gymnastic floor exercise" , "Face-to-the-floor exercise" .)