Not to be taken as shy (8)
I believe the answer is:
reserved
'shy' is the definition.
(reserved can mean shy or timid)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for reserved that I've seen before include "Reticent; put by" , "not forthcoming" , "Spoken for" , "Aloof" , "Slow to show emotion" .)