With wet land to the west, I leave dry land (4,6)
I believe the answer is:
gobi desert
'dry land' is the definition.
'with wet land to the west i leave' is the wordplay.
'with wet land' becomes 'bog' (I can't justify this - if you can you should give a lot more credence to this answer).
'to the west' says the letters should be written backwards.
'leave' becomes 'desert' (deserting is a kind of leaving).
'bog' written backwards gives 'gob'.
'gob'+'i'+'desert'='GOBI DESERT'
(Other definitions for gobi desert that I've seen before include "Region of Central Asia" , "Asian wilderness" , "dry expanse" , "Be intelligible" , "Mongolian wasteland" .)