Go with the current doctor, if time (5)
I believe the answer is:
drift
'go with the current' is the definition.
(as in drifting in the water)
'doctor if time' is the wordplay.
'doctor' becomes 'Dr' (abbreviation).
'time' becomes 't' (abbreviation).
'dr'+'if'+'t'='DRIFT'
(Other definitions for drift that I've seen before include "go with the tide" , "move around without end" , "Slide" , "Wander aimlessly" , "Float along; heap of snow" .)