8  Have on state location (4)

 9  Rhetoric with nothing much put out by Spain after article there (9)

10 Make sure, scratching heads and shaking until... got it! (6)

11 Opiate could be nice little earner? (8)

12 Projection left out relatively unimportant part (8)

14 Money for pop by Jove! (6)

16 Under pressure to remove drug for pain relief (4)

17 13's a result of pressure change (5)

18 See 4 Down

19 Land Rover? (6)

21 Glimpse of having warmth after cold periods (8)

23 Bones joined at the middle? (8)

26 Spring one plugged? (6)

27 Logical choice among those who break and those who fix things (9)

28 See 7 Down

 2  Those in command of rank and file? (8)

 3  New arrangement as theatre has Hollywood feature (6)

 4/18A          13 rocks, boxes rocky and round (8)

 5  They expedite 13 when queen replaces punishment (8)

 6  Please stop at the middle, for example (6)

 7/28  Nick's team (8)

13 Appearing top, bottom, left and right, currently heads or tails perhaps (5)

15 Swirling elements to promote the intensity of light shower (10)

17 Reflex response from Belgium, missing one being addressed (5,3)

18 Need 24 components put together as compound (8)

20 Lyrical manner needs 24 compounded with good heart (6)

22 Surprise with early growth (6)

24 Show off when put on 13 (4)

25 Creator of Adrian M's pudding? (4)