Doctor, say, has small bits left (5)
I believe the answer is:
dregs
'bits left' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'doctor say has small' is the wordplay.
'doctor' becomes 'Dr' (abbreviation).
'say' becomes 'eg'.
'has' means one lot of letters go next to another.
'small' becomes 's' (abbreviation - e.g. clothes size).
'dr'+'eg'+'s'='DREGS'
Can you help me to learn more?
(Other definitions for dregs that I've seen before include "Wine or coffee residue" , "Lees - riffraff" , "Residue, lees" , "Most worthless part (of anything)" , "Sediment at bottom of drink" .)