I help regulars, uprooting exceptional plant (6)
I believe the answer is:
dahlia
'plant' is the definition.
(dahlia is a kind of plant)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for dahlia that I've seen before include "Tuberous garden plant" , "Tuberous plant with showy flowers" , "Strangely, Ali had this flower" , "Composite" , "Showy bloom" .)