A growing boy, possibly in the kitchen (5)
I believe the answer is:
basil
'a growing boy' is the definition.
'Basil' can be an answer for 'boy' (I've seen this before). I am not sure about the 'a growing' bit.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for basil that I've seen before include "Boy - herb" , "Fragrant herb" , "Aromatic herb with purplish-green leaves" , "Mediterranean herb" , "A herb; --- Brush, Fawlty" .)