Cat's picking up green piece of land (6)
I believe the answer is:
ocelot
'cat's' is the definition.
(ocelot is a kind of cat)
'picking up green piece of land' is the wordplay.
'picking up' shows that the letters should be reversed in order.
'green' becomes 'eco' (abbreviation for ecological).
'piece of land' becomes 'lot' (lot is a kind of piece of land).
'eco' reversed gives 'oce'.
'oce'+'lot'='OCELOT'
(Other definitions for ocelot that I've seen before include "Big cat" , "Send animal to Cole" , "Wild cat of the Americas" , "South and Central American wildcat" , "American wild cat" .)