ton·tine (tntn, tn-tn)
n.
1. An investment plan in which participants buy shares in a common fund and receive an annuity that increases every time a participant dies, with the entire fund going to the final survivor or to those who survive after a specified time.
2. Each member's share of a tontine.
3. The subscribers to a tontine.
Thank you all - I looked up tontine in the dictionary and understood that bit, but couldn't work out where "clan" came into it, now I see it. Thanks again.