Bound to be particular (7)
I believe the answer is:
certain
I believe this is a double definition.
'bound to' is the first definition.
(similar in meaning)
'particular' is the second definition.
(I've seen this before)
'be' acts as a link.
(Other definitions for certain that I've seen before include "Unquestionable" , "Indisputable" , "Particular" , "Proved beyond doubt" , "Known beyond doubt" .)