Area with little moisture and 500 gnarled trees (6)
I believe the answer is:
desert
'area' is the definition.
(I know that desert is a type of area of land)
'500 gnarled trees' is the wordplay.
'500' becomes 'd' (Roman numeral for 500).
'gnarled' is an anagram indicator (gnarled can mean twisted).
'trees' is an anagram of 'esert'.
'd'+'esert'='DESERT'
'with little moisture and' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for desert that I've seen before include "Abandon in barren terrain" , "part of Africa?" , "expanse of land without water" , "sands" , "Leave; arid area" .)