Question Author
For anyone interested I've now managed to post the clues:
18a. Shelf by a fireplace for heating kettles and pans; a cooker’s hotplate; a sprite such as Puck; a rustic; a male ferret; or, a target peg in quoits (3)
20a. Word for a find originally, later a success; a strike of a ball, target or anything else; a witticism; a lucky chance; a single visit to a website; or, a dose of a narcotic (3)
45a. Any chapeau typically with a shaped crown, originally designed to draw attention to a man’s head and emphasise his social status; or, by extension, one’s capacity or role (3)
47a. A watery expanse where one is said to be when confused or drifting like a ship that has lost its bearings (3)