Lip seen by doctor? Clear the bed! (6)
I believe the answer is:
'the bed' is the definition.
(I have seen 'Clean bed' mean 'dredge' so perhaps 'bed' could also mean 'dredge')
'lip seen by doctor? clear' is the wordplay.
'lip' becomes 'edge' (I've seen this before).
'seen by' says to put letters next to each other.
'clear' means to remove the middle letters (I've seen 'cleared' mean this (the inside letters are cleared out)).
'doctor' with its centre removed is 'dr'.
'edge' after 'dr' is 'DREDGE'.
(Other definitions for dredge that I've seen before include "Clean mud as from silted harbour" , "Clear a channel" , "Dig out mud (from a river, harbour, etc)" , "Clear out (a waterway)" , "Dig up mud from river or canal bed" .)