Chile cultivated new plant (6)
I believe the answer is:
Here is my best explanation:
'plant' is the definition.
(lichen is a kind of plant)
'chile cultivated new' is the subsidiary indication.
'cultivated' indicates an anagram.
'new' becomes 'n'.
'chile' anagrammed gives 'liche'.
(Other definitions for lichen that I've seen before include "Compound plant of fungus and alga", "Plants found on tree trunks etc", "Tiny plants growing on rocks and treetrunks", "Simple plant often found growing on rocks", "Symbiotic organism growing on a tree trunk or rock", "Compound moss-like plant", "Crusty, tufty growth on trees and stones", "It's found on rocks and tree-trunks", "Plant growing on stone" and "Tiny green-grey plants growing on rocks and trees".)