Put window in and looked over lake (6)
I believe the answer is:
glazed
'put window in' is the definition.
(as in glazing a window)
'looked over lake' is the wordplay.
'looked' becomes 'gazed' (gazing is a kind of looking).
'over' is an insertion indicator.
'lake' becomes 'l' (geographical abbreviation).
'gazed' enclosing 'l' is 'GLAZED'.
'and' is the link.
(Other definitions for glazed that I've seen before include "With window panes fitted" , "Polished" , "Enclosed or covered with glass" , "expressionless" , "Fitted or covered with glass" .)