Defeat inspiring passion with defensive system (8)
I believe the answer is:
firewall
'defensive system' is the definition.
(eg a computer firewall)
'defeat inspiring passion with' is the wordplay.
'defeat' becomes 'fall' (fall can mean a loss or defeat).
'inspiring' indicates putting letters inside.
'passion' becomes 'ire' (ire is passionate anger).
'with' becomes 'w' (abbreviation).
'ire'+'w'='irew'
'fall' enclosing 'irew' is 'FIREWALL'.
(Other definitions for firewall that I've seen before include "A protective system" , "Computer security system against online attack" , "Software protection for computer" , "network protection" .)