Row about Doctor Wood (6)
I believe the answer is:
timber
'wood' is the definition.
(I've seen this before)
'row about doctor' is the wordplay.
'row' becomes 'tier' (a tier is a row of things).
'about' indicates putting letters inside.
'doctor' becomes 'MB' (Bachelor of Medicine, Medicinae Baccalaureus).
'tier' enclosing 'mb' is 'TIMBER'.
(Other definitions for timber that I've seen before include "Warning cry that a tree is about to fall" , "Ash perhaps" , "Deal possibly" , "Lumberjack's warning call" , "Mind the falling tree!" .)