Join a clan, complete clan milestones, and earn enough clan XP to level up your clan and unlock the next level of rewards.
Players will earn clan rewards exactly the same way they did last season.
Destiny 2‘s first major DLC expansion, Curse of Osiris, may be pissing off players for removing content from the vanilla game and introducing a wildly unbalanced new exotic weapon, but, hey, at least there are some new clan rewards to earn.
In other words, join a clan and play the game, and you should be good.