Humble, unassuming (6)
I believe the answer is:
modest
I believe this is a double definition.
'humble' is the first definition.
(I know that humble can be written as modest)
'unassuming' is the second definition.
(similar in meaning)
(Other definitions for modest that I've seen before include "Free from pomp or affectation" , "Humble, not pretentious or showy" , "Not conceited, unassuming" , "Avoiding indecency; unassuming" , "Mussorgsky, nominally?" .)