Clani

Clani was the portmanteau of Clyde and Rani. The word was invented by Luke at Oxford University, and was, for an indefinite period of time, shared privately between the three. Sarah Jane first became aware of the word on Luke's initial meeting with Sky around the time of the introduction of the SerfBoard.

Rani wrote off the term as a lame attempt at humour, but also asked Luke, "don't call us that." (SJA: The Man Who Never Was)

Behind the scenes
Clani is a term that originated in fandom, and was in particular use amongst people who wrote fan fiction. It described a kind of story that focused on the relationship between Clyde and Rani, often stressing its romantic possibilities.