1 Where a rider stores things (9)
6 Old gold coin (5)
9 Madman or woman (7)
10 Derived or originating externally (9)
11 The bleating of sheep (7)
12 Geometric pattern that is repeated at every scale and so cannot be represented by classical geometry (7)
13 Area of the Atlantic where planes and ships are alleged to disappear (7,8)
18 Alcoholic drink flavoured with the fruit of the blackthorn (4,3)
20 Caustic remark(s) (7)
22 Maelstrom (9)
23 Favouring the selection of a special group (7)
24 First English circumnavigator (5)
25 Lizard of Africa and Madagascar able to change skin colour and having a projectile tongue (9)

1 Spiced hot milk with rum or wine (8)
2 Large extinct reptile (8)
3 Triangular sail used especially in the Mediterranean (6)
4 Forearm flexing muscle (6)
5 Pass the bounds of good taste, etc. (2,3,3)
6 Cane sugar from Guyana (8)
7 One-tenth of a Roman legion (6)
8 Either of two lymph glands on the side of the root of the tongue (6)
14 A hoofed animal (8)
15 --- fluid, the fluid in which the embryo is suspended (8)
16 The lead in "lead" pencils, plumbago (8)
17 Capital of Alberta, Canada (8)
18 The man who bought Alaska (6)
19 Female character in Twelfth Night (6)
20 Outermost membrane of the eyeball (6)
21 City of northeastern Brazil on the Atlantic (6)