Catching up on this one too ...
12a English astronomier who calculated the position of a supposed planet beyond Uranis which later led to the discovery of Neptune (5) a?a?s
48d a heap of root vegetables protected by a layer of earth of straw (5) c?a?p
18a a type of clamp like device secured of the fingerboard of a fretted musical instrument to raise the pitch of the strings (4) c?p?
52d dish consisting of a slice of veal or beef rolled round a savoury stuffing (5) o?i?e