ACROSS

 1 A North African capital (7)
 5 Seek after (7)
 9 To malign (7)
10 Canadian city (7)
11 Sky-blue (5)
12 Ignore (9)
13 Loquacious (9)
15 Perpendicular (5)
16 Correct in every detail (5)
18 Without hestitation (4,1,4)
21 Suspend indefinitely (3,2,4)
24 Haggard (5)
25 A cooling fruit juice drink (7)
26 Original (7)
27 Make out (7)
28 Seriousness (7)

DOWN

 1 To draw (7)
 2 Progressing by degrees (7)
 3 High-spirited (9)
 4 An amphetamine drug (5)
 5 As it were (2,2,5)
 6 Extensive (5)
 7 Curved inwards (7)
 8 At customer's demand (2,5)
14 Gained by crime (3-6)
15 An imaginary paradise (7-2)
16 Unprotected (7)
17 Ingenous (7)
19 Famous US escapologist (7)
20 Absoultely (7)
22 Magnanimous (5)
23 Effort (5)