A brief, for example, is for the defence (5)
I believe the answer is:
aegis
'defence' is the definition.
(I've seen this before)
'a brief for example is' is the wordplay.
'brief for example' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin; 'brief' asks for a short form).
'a'+'eg'+'is'='AEGIS'
'for the' acts as a link.
(Other definitions for aegis that I've seen before include "Auspices" , "Protection (originally of Zeus)" , "Protection or sponsorship" , "Protection (of someone)" , "Protection or support" .)