Quietude (5)
I believe the answer is:
peace
'quietude' is the definition.
(I know that peace is a type of quietude)
This is the entire clue.
(Other definitions for peace that I've seen before include "Quiet companion" , "''And I shall have some ... there, for ... comes dropping slow'' (WB Yeats)" , "Freedom from disturbance, tranquillity" , "an answer to all clues, initially" , "See 1" .)