Fresh, right after exercising (4)
I believe the answer is:
pert
'fresh' is the definition.
(I've seen this before)
'right after exercising' is the wordplay.
'right' becomes 'rt' (abbreviation as in Rt Hon- the Right Honourable).
'after' means one lot of letters go next to another.
'exercising' becomes 'pe' (abbreviation for Physical Education).
'rt' after 'pe' is 'PERT'.
(Other definitions for pert that I've seen before include "Forward - saucy" , "Impudent, cheeky" , "Saucy, lively" , "Irreverent or saucy" , "Saucy and chipper" .)