Bores the doctor with ailments (6)
I believe the answer is:
drills
'bores' is the definition.
(I've seen this before)
'the doctor with ailments' is the wordplay.
'the doctor' becomes 'dr' ('Dr' can be a synonym of 'doctor').
'with' is a charade indicator (letters next to each other).
'ailments' becomes 'ills' ('ill' can be a synonym of 'ailment').
'dr'+'ills'='DRILLS'
(Other definitions for drills that I've seen before include "they bore" , "monkeys" , "Bores in army exercises" , "Trains, in military fashion" , "Teaches by repetition" .)