Developer buried rocks across lake (7)
I believe the answer is:
builder
'developer' is the definition.
('builder' can be a synonym of 'developer')
'buried rocks across lake' is the wordplay.
'rocks' indicates anagramming the letters.
'across' is an insertion indicator.
'lake' becomes 'l'.
'buried' anagrammed gives 'buider'.
'buider' enclosing 'l' is 'BUILDER'.
(Other definitions for builder that I've seen before include "One involved in construction" , "Erector of houses" , "Bob the - - (TV)" , "Constructor" , "Construction worker" .)