Vegetable: try eating every bit (7)
I believe the answer is:
shallot
'vegetable' is the definition.
(I know that shallot is a type of onion)
'try eating every bit' is the wordplay.
'try' becomes 'shot' (both can mean an attempt).
'eating' indicates putting letters inside.
'every bit' becomes 'all' (all of it).
'shot' going around 'all' is 'SHALLOT'.
(Other definitions for shallot that I've seen before include "bit of salad" , "Type of onion" , "Small onion" , "Host all with kind of onion" , "Onion-like plant with clusters of bulbs" .)