Ground wanted around lake? Don't build on it, surely? (7)
I believe the answer is:
wetland
'don't build on it surely?' is the definition.
(wetlands are not suitable for building on)
'ground wanted around lake?' is the wordplay.
'ground' indicates anagramming the letters (grind the letters ).
'around' is an insertion indicator.
'lake?' becomes 'l'.
'wanted' anagrammed gives 'wetand'.
'wetand' going around 'l' is 'WETLAND'.
(Other definitions for wetland that I've seen before include "Marshy area" , "Boggy territory" .)