A workman in better condition (6)

I believe the answer is:
fitter
'a workman' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for fitter that I've seen before include "better equipped" , "Workman" , "Mechanic" , "Healthier" , "to get in better shape" .)
