Rabble-rousing nurses head off Mary Berry in Glasgow (7)
I believe the answer is:
bramble
'berry in glasgow' is the definition.
The answer and definition can be both plants as well as being singular nouns.
Maybe you can see a link between them that I can't see?
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for bramble that I've seen before include "Thorny bush" , "Gather fruit" , "Wild thorny shrub" , "Blackberry plant" , "Rough, prickly shrub" .)