Chastened (7)
I believe the answer is:
subdued
'chastened' is the definition.
('subdue' can be a synonym of 'chasten')
This is all the clue.
(Other definitions for subdued that I've seen before include "Chastened" , "'Restrained, low-key (7)'" , "Overpowered" , "Quiet; repressed" , "'Quieted, cowed (7)'" .)