8 down
Protect
upstanding
US
agent
on
border
(6)
Protect upstanding US agent on border (6)
hints
0
checks
0
hints
The definition is at the beginning of the clue.
How the clue works
Protect is your definition, meaning to guard something. For the wordplay, take FED (a US agent) and stand it up, i.e. reverse it, since it's clued "upstanding", giving DEF, then tack on END for "border" — DEF plus END gives you the answer.