Plain and simple variety of citrus (6)
I believe the answer is:
rustic
'plain' is the definition.
(I've seen this before)
'of citrus' is the wordplay.
'of' indicates anagramming the letters (the answer comes from or 'of' the letters).
'citrus' is an anagram of 'RUSTIC'.
'and simple variety' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for rustic that I've seen before include "Characteristic of rural life" , "Of the country, bucolic" , "Rural, countrified" , "Simple and unsophisticated as in the country" , "Charmingly simple" .)