Previously guards live and die, showing respect (9)
I believe the answer is:
obedience
'respect' is the definition.
('obedience' can be a synonym of 'respect')
'previously guards live and die' is the wordplay.
'previously' becomes 'once' (I've seen this before).
'guards' means one lot of letters goes inside another.
'live' becomes 'be' ('be' can be a synonym of 'live').
'and' means one lot of letters go next to another.
'be'+'die'='bedie'
'once' enclosing 'bedie' is 'OBEDIENCE'.
'showing' acts as a link.
(Other definitions for obedience that I've seen before include "Vow" , "Observance of the rules" , "Compliance, submission" , "Compliance with an order or law" , "special devotion" .)