Jeers when military quarters seen (8)
I believe the answer is:
barracks
'jeers' is the definition.
('barrack' can be a synonym of 'jeer')
'military quarters seen' is the wordplay.
'military quarters' becomes 'barrack' (barrack is a kind of military quarters).
'seen' becomes 's' (this could be a standard abbreviation of which I'm unaware).
'barrack'+'s'='BARRACKS'
'when' is the link.
Can you help me to learn more?
(Other definitions for barracks that I've seen before include "Audibly disapproves of" , "men who fight in houses here" , "Jeers in soldiers' quarters" , "Building for military personnel" , "Military building(s)" .)