Rough copy for doctor at the back (5)
I believe the answer is:
draft
'rough copy' is the definition.
(I've seen this in another clue)
'doctor at the back' is the wordplay.
'doctor' becomes 'Dr' (abbreviation).
'at' says to put letters next to each other.
'the back' becomes 'aft' (at the back of a ship).
'dr'+'aft'='DRAFT'
'for' is the link.
(Other definitions for draft that I've seen before include "plan outlined" , "A money order for US conscription" , "Sketch; money order" , "Provisional document" , "Early version of text" .)