Lake; no more than (4)
I believe the answer is:
mere
I believe this clue is a double definition.
'lake' is the first definition.
(I know that mere is a type of lake)
'no more than' is the second definition.
(eg a mere mortal is no more than a mortal)
(Other definitions for mere that I've seen before include "DDwater" , "Lake (poetic); Maori war club" , "a drop of water" , "Without additions or modifications" , "Lake; Wiltshire town" .)