They are mostly rough and ribald (6)
I believe the answer is:
earthy
'ribald' is the definition.
(I've seen this in another clue)
'they are mostly rough' is the wordplay.
'mostly' means to remove the last letter (most but not all of the word).
'rough' indicates an anagram (a rough or broken ordering of the letters).
'they'+'are'='theyare'
'theyare' with its final letter removed is 'theyar'.
'theyar' with letters rearranged gives 'EARTHY'.
'and' is the link.
(Other definitions for earthy that I've seen before include "Coarse, vulgar" , "Coarse; unsophisticated" , "Of the soil, lusty" , "Blue" , "Unrefined - the ray (anag)" .)