What tub-thumpers do around central Greenford is good to see (6)
I believe the answer is:
ornate
I'm afraid I can't explain this answer.
Can you help me to learn more?
(Other definitions for ornate that I've seen before include "Excessively decorated" , "Lavishly decorated" , "Elaborate, flowery" , "Elaborately decorated, perhaps overdone" , "Over-decorated" .)