Quiet and uncommunicative (8)
I believe the answer is:
taciturn
'quiet and uncommunicative' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for taciturn that I've seen before include "Habitually uncommunicative, saying little" , "Aloof" , "Not inclined to conversation" , "Reticent" , "Uncommunicative, of few words" .)