Messenger, out of uniform, going round with culinary herb (9)
I believe the answer is:
coriander
'herb' is the definition.
(I've seen this before)
'messenger out of uniform going round with culinary' is the wordplay.
'messenger' becomes 'courier' ('courier' can be a synonym of 'messenger').
'out of' indicates named letters should be taken away.
'uniform' becomes 'u' (phonetic alphabet: alpha, bravo, charlie etc.).
'going round' means one lot of letters goes inside another.
'with culinary' becomes 'and' (I am not sure about this - if you are sure you should believe this answer much more).
'courier' with 'u' taken out is 'corier'.
'corier' going around 'and' is 'CORIANDER'.
Can you help me to learn more?
(Other definitions for coriander that I've seen before include "leaves for cooking" , "Culinary herb" , "Carried on with the strange herb" , "Aromatic herb" , "Plant with spicy fruit" .)