As letters must be, coming out of Dorset (6)
I believe the answer is:
sorted
'as letters must be coming out' is the definition.
I can't judge whether this definition defines the answer.
'of dorset' is the wordplay.
'of' indicates anagramming the letters (the answer comes from or 'of' the letters).
'dorset' anagrammed gives 'SORTED'.
Can you help me to learn more?
(Other definitions for sorted that I've seen before include "Shuffled into desired order" , "Job done!" , "Classified - problem solved!" , "Put into correct sequence" , "Put into order" .)