Kept being shy (8)
I believe the answer is:
reserved
I believe this is a double definition.
'kept' is the first definition.
(to keep is to reserve or hold onto)
'shy' is the second definition.
(reserved can mean shy or timid)
'being' acts as a link.
(Other definitions for reserved that I've seen before include "Booked, being unemotional" , "cool" , "Spoken for" , "Uncommunicative, not extrovert" , "Aloof" .)