Exercise before small drink (5-2)
I believe the answer is:
press-up
'exercise' is the definition.
(I know that press-up is a type of bodyweight exercise)
'before small drink' is the wordplay.
'before' becomes 'pre' (prefix meaning 'before').
'small' becomes 's' (abbreviation - e.g. clothes size).
'drink' becomes 'sup' (to sup is to drink).
'pre'+'s'+'sup'='PRESS-UP'
(Other definitions for press-up that I've seen before include "Gymnastic floor exercise" , "Form of arm exercise" , "PE exercise" , "Arm exercise while lying face down" , "Keep-fit exercise" .)