High mountain with a lake and parking (3)
I believe the answer is:
alp
'high mountain' is the definition.
(I've seen this before)
'a lake and parking' is the wordplay.
'lake' becomes 'L' (geographical abbreviation).
'and' means one lot of letters go next to another.
'parking' becomes 'p' (abbreviation on road signs).
'a'+'l'+'p'='ALP'
'with' acts as a link.
(Other definitions for alp that I've seen before include "Swiss mountain" , "High mountain" , "Mountain pasture" , "One of a European mountain range" , "Mont Blanc, for example" .)