Clever names are just about free-associating until something's funny. Just go through lists of words related to the subject and try fitting them together. The more you do it, the better you get at it, but in the hopefully immortal words of the hilarious Tim Minchin in his song "dark side": "Clever never made no one rich."
With this one, I went through crap like Tiger07, James Bengal, Spyger, The Spy Who Mauled Me, etc. before I took a step back, thought "secret agent," remembered "agent orange," the chemical weapon used in 'Nam, and thought "hey, he's a secret agent, and he's orange! Both popularly familiar phrases together make a catchy and kind of funny name!"
Secret Agent Orange also works because it's comprised of trochees (two syllable words with the emphasis on the first syllable). xkcd does a great comic explaining why that means anything: [link]
The image itself is a good one too.
With this one, I went through crap like Tiger07, James Bengal, Spyger, The Spy Who Mauled Me, etc. before I took a step back, thought "secret agent," remembered "agent orange," the chemical weapon used in 'Nam, and thought "hey, he's a secret agent, and he's orange! Both popularly familiar phrases together make a catchy and kind of funny name!"