Lake once also largely surrounded by piece of land (4,3)
I believe the answer is:
aral sea
'lake' is the definition.
(I've seen this before)
'also largely surrounded by piece of land' is the wordplay.
'largely' means to remove the last letter (most but not all of the letters).
'surrounded by' means one lot of letters goes inside another.
'piece of land' becomes 'area' (geographical area).
'also' with its final letter taken away is 'als'.
'als' placed within 'area' is 'ARAL SEA'.
'once' is the link.
(Other definitions for aral sea that I've seen before include "Large lake now largely desert" , "Shrunken lake" , "Saltwater lake" .)