Fruit that stinks when filled with honey (6)
I believe the answer is:
pomelo
'fruit' is the definition.
(pomelo is a kind of fruit)
'stinks when filled with honey' is the wordplay.
'stinks when' becomes 'poo' (I am not sure about this - if you are sure you should believe this answer much more).
'filled with' is an insertion indicator.
'honey' becomes 'mel' (Latin name for honey).
'poo' placed around 'mel' is 'POMELO'.
'that' is the link.
Can you help me to learn more?
(Other definitions for pomelo that I've seen before include "Largest citrus fruit" , "Shaddock" .)