Skip about on exercise run (5)
I believe the answer is:
caper
'skip' is the definition.
(I've seen this before)
'about on exercise run' is the wordplay.
'about' becomes 'ca' (abbreviation for 'circa'**).
'on' is a charade indicator (letters next to each other).
'exercise' becomes 'pe' (Physical Education).
'run' becomes 'r' (cricket abbreviation).
'ca'+'pe'+'r'='CAPER'
(Other definitions for caper that I've seen before include "Recap about prank" , "practical joke" , "Antic, prank" , "Pickle ingredient" , "Frolic - plant with edible buds" .)