Vegetable makes detective sick (4)
I believe the answer is:
dill
'vegetable' is the definition.
The answer and definition can be both things that one consumes for nourishment as well as being singular nouns.
Maybe there's a link between them I don't understand?
'detective sick' is the wordplay.
'detective' becomes 'd' (this might be a standard abbreviation of which I'm unaware).
'sick' becomes 'ill' (synonyms).
'd'+'ill'='DILL'
'makes' acts as a link.
Can you help me to learn more?
(Other definitions for dill that I've seen before include "Pickle flavouring" , "Herb with thread-like foliage used as seasoning" , "Herb used in cooking" , "Herb of parsley family" , "Medicinal herb" .)