Calm and unemotional (6)
I believe the answer is:
stolid
'calm and unemotional' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for stolid that I've seen before include "Showing little or no interest or emotion" , "Calm, emotionless" , "Unemotional, unresponsive" , "Not excitable or emotional" , "Not excitable, unemotional" .)