Is husband behind bar cast out? (6)
I believe the answer is:
banish
'cast out?' is the definition.
('banish' can be a synonym of 'cast out')
'is husband behind bar' is the wordplay.
'husband' becomes 'h' (abbreviation).
'behind' is a charade indicator (letters next to each other).
'bar' becomes 'ban' (bar can mean to ban or prohibit).
'is'+'h'='ish'
'ish' put after 'ban' is 'BANISH'.
(Other definitions for banish that I've seen before include "Send away (as punishment)" , "Exile (someone)" , "Expel or expatriate" , "Send into exile" , "outlaw" .)