Though Stephen's no chicken, there's some progress (4)
I believe the answer is:
step
'some progress' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for step that I've seen before include "Measure - pace" , "short distance" , "Place foot on as with a pest" , "Stage - pace" , "Move a little way" .)