But it means nothing! It's a b@staardiation of an Italian word! Ask any Italian what "risico" means, and they'll probably look at you like you're stupid.
Actually, isn't it a bastardisation of an english word?
Isn't it both? An equation like:
1
risk (English) + 1
rischio (Italian), shaken and not stirred =
risico (Flemingian)
Which makes me think: it seems to me that Fleming, here, makes a mistake common to many writers when they want to have foreign characters making mistakes when they speak. I can't imagine an Italian with the minimal level of english required to make a conversation with Bond forging the word "risico" while trying to say "risk" (he would know English words dont end with -o, and if he were to forge a word he would do it otherwise, or simply keep the real Italian word).
Another frequent mistake is to make foreign characters deliver perfectly formed lines, in clipped english, then say the most common and simple words in their own languages. This is not how it works! Foreign (and not bilingual) characters make syntax mistakes, and stumble upon "faux amis" from their own language; how one makes mistakes while speaking English depends on his mother tongue actually, and writers very seldom pay attention to that. For instance, as far as I've observed, Russian people don't say "Da" and "Spassiba" instead of "Yes" and "Thank you" while speaking English in real life, so it shouldn't be used in fiction works to make them "sound" Russian.

My 2 rubles

Anyhow, "risico" is the Dutch word for "risk" (no,
really), so let's supppose the Italian speaker using it had Dutch origin, keeping up with the tradition of "mixed blood" characters in Fleming