Clan XP is essentially the amount of XP gained by a player while belonging to a specific clan. If a player cannot gain XP due to reaching the cap of 200m XP in a skill, no Clan XP can be gained while training that skill. There are no restrictions on how much Clan XP a player can gain aside from this.
The "cap" on Clan XP is determined by restrictions that already exist on regular XP gained by players. Realistically, if an account gains no XP prior to joining a clan and reaches the 5.4 Billion XP cap by achieving 200m XP in all skills while belonging to that clan, the maximum amount of Clan XP a member can gain is 5,399,998,846 XP. This is due to new accounts starting with Level 10 Constitution which means they start at 1154 XP, rather than 0, when their Clan XP would start.
~ Sicariu
Leader of