A doctor regularly pulls soldier fit to walk (8)
I believe the answer is:
ambulant
'fit to walk' is the definition.
(ambulant means able to walk around)
'a doctor regularly pulls soldier' is the wordplay.
'a doctor' becomes 'amb' (I can't explain this - if you can you should believe this answer much more).
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'soldier' becomes 'ant' (I've seen this before).
The alternate letters of 'pulls' are 'ul'.
'amb'+'ul'+'ant'='AMBULANT'
(Other definitions for ambulant that I've seen before include "Moving about, able to walk" , "Walking, moving around" , "Of patient, able to walk" , "Able to walk, not confined to bed" .)