Fellow doctor supports beloved, a source of sweetness (9)
I believe the answer is:
honeycomb
'a source of sweetness' is the definition.
(I've seen this before)
'fellow doctor supports beloved' is the wordplay.
'fellow doctor' becomes 'comb' (I can't justify this - if you can you should believe this answer much more).
'supports' means one lot of letters go next to another (bottom letters provide a support for the top ones).
'beloved' becomes 'honey' ('honey' can be a synonym of 'beloved').
'comb' after 'honey' is 'HONEYCOMB'.
Can you help me to learn more?
(Other definitions for honeycomb that I've seen before include "Bees' maze" , "Edible structure of hexagons" , "source of sweetness" , "pattern of cells" , "Construction in hive" .)