Exercise
'exercise' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for sit-up that I've seen before include "Physical exercise" , "Exercise designed to strengthen stomach muscles" , "Exercise done on the floor" .)
'exercise' is the definition.
(I know that exercise can be written as exert)
This is the entire clue.
(Other definitions for exert that I've seen before include "Make use of" , "Cause (oneself) to make a strenuous effort" , "Strain" , "Bring (force) to bear" , "Bring into use, strength or influence" .)
'exercise' is the definition.
(both can mean to employ or make use of)
This is the entire clue.
(Other definitions for wield that I've seen before include "Brandish a weapon or exert power" , "Use (weapon, authority)" , "exercise" , "Handle - manage" , "Hold and use (a weapon or tool)" .)
'exercise' is the definition.
(I know that press-up is a type of arm exercise)
This is all the clue.
(Other definitions for press-up that I've seen before include "Keep-fit exercise" , "Form of arm exercise" , "Arm exercise while lying face down" , "PE exercise" , "Face-to-the-floor exercise" .)
'exercise' is the definition.
(I know that exercise can be written as use)
This is the entire clue.
(Other definitions for use that I've seen before include "Practise" , "Bring into play" , "Habitually employ" , "Employ; consume" , "Put into service, do something with" .)