Robust binding (9)
I believe the answer is:
strapping
I believe this is a double definition.
'robust' is the first definition.
(similar in meaning)
'binding' is the second definition.
(strapping is a kind of binding)
(Other definitions for strapping that I've seen before include "Big" , "Burly" , "stalwart" , "Brawny" , "Tying up" .)