Taciturn, reticent (8)
I believe the answer is:
reserved
I believe this is a double definition.
'taciturn' is the first definition.
(thesaurus)
'reticent' is the second definition.
(synonyms)
(Other definitions for reserved that I've seen before include "Quiet, not given to showing emotion" , "Slow to reveal emotion" , "Held back, set aside" , "not forthcoming" , "Booked, being unemotional" .)