Despejar and despejarse can both mean “to clear up” according to Collins Dictionary, former meaning to clear something up, latter something clears itself up, e.g. weather. Memrise always marks despejar as a translation of “to clear up” as wrong. Perhaps this should be revised?
Regards, Christopher
Can you repost this in the forum for the kind of Spanish you are studying? It is possible that the people in charge of making changes to the Spanish courses will see it here.
I take it you are doing one of memrise’s own courses?
Can you post a link to which one?
For example, this is the thread to post in for Spanish 1-7 by memrise:
If this is the right forum, you could just repost your comment there.