Drug runners with no heart left one for something to eat (6)
I believe the answer is:
muesli
'something to eat' is the definition.
(muesli is a kind of food)
'drug runners with no heart left one' is the wordplay.
'drug runners' becomes 'mes' (I can't justify this - if you can you should give a lot more credence to this answer).
'with' is an insertion indicator.
'no' becomes 'refusal' (refusing is saying no).
'heart' indicates the central letters.
'left one' becomes 'li' (left abbreviation plus m).
The middle letter of 'refusal' is 'u'.
'mes' enclosing 'u' is 'mues'.
'mues'+'li'='MUESLI'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for muesli that I've seen before include "Breakfast mixture of dry cereals and fruits" , "Swiss breakfast?" , "Type of breakfast cereal" , "Breakfast cereal mix" , "Swiss cereal" .)