At least four supports (6)
I believe the answer is:
braces
'supports' is the definition.
(brace is a kind of support)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for braces that I've seen before include "Dental appliances and pairs" , "bolsters" , "Straps used to keep trousers up" , "Appliances to correct dental irregularities" , "Over-the-shoulders supporters" .)