Urge to increase small exercises (5-3)
I believe the answer is:
press-ups
'exercises' is the definition.
(press-up is a kind of exercise)
'urge to increase small' is the wordplay.
'urge' becomes 'press' (synonyms).
'to increase' becomes 'up' (upping is a kind of increasing).
'small' becomes 's' (abbreviation - e.g. clothes size).
'press'+'up'+'s'='PRESS-UPS'
(Other definitions for press-ups that I've seen before include "Exercises done facing the floor" , "Exercises performed face down" .)