Some pale echo for a doctor (5)
I believe the answer is:
leech
'a doctor' is the definition.
(I've seen this before)
'some pale echo for' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'LEECH' can be found hidden inside 'pale echo for'.
(Other definitions for leech that I've seen before include "Old medical attendant" , "Old doctor" , "Small worm once used for blood-letting, or a parasitical person" , "Parasite - hanger-on" , "One used to bleed" .)