Strict doctor with papers (5)
I believe the answer is:
rigid
'strict' is the definition.
(synonyms)
'doctor with papers' is the wordplay.
'doctor' becomes 'rig' (I've seen this in other clues).
'with' says to put letters next to each other.
'papers' becomes 'id' (identification papers).
'rig'+'id'='RIGID'
(Other definitions for rigid that I've seen before include "Stiff, unmoving" , "Uncompromising" , "Stiff, unbending" , "Unable to bend" , "Incapable of or resistant to bending" .)