Plant roses at front except in centre (7)
I believe the answer is:
rhubarb
'plant' is the definition.
(rhubarb is a kind of plant)
'roses at front except in centre' is the wordplay.
I cannot really see how this works, but
'except' could be 'bar' ('bar' can mean 'except' or 'not including') and 'bar' is found within the answer.
'centre' could be 'hub' (hub is a kind of centre) and 'hub' is located in the answer.
A single letter 'r' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for rhubarb that I've seen before include "Noise of actors simulating conversation" , "Plant grown for its stalks" , "Stage chatter" , "Plant stalks eaten as fruit" , "An edible red stalk" .)