6  Seed to pile into heaps for showy bird (7)

 7  Tire out and unrestrainedly push pet pups (3,2)

 9  Greek characters to fully satisfy in retrospect (4)

10 How despots rule beyond a doubt (10)

11 Dubiously bring own product for making gravy (8)

13 Sociable criminal (6)

15 Address supplication, we're told, for victim (4)

17 Stretch one's neck in order to see wading bird (5)

18 Basis essentially and component of concrete (4)

19 Capital city originally loved old northern professor (6)

20 Body of divine rulers disconcerted the chary (8)

23 Shambolic chef fed rat! Highly imaginative but implausible (3-7)

26 Additional soldiers going into Middle East (4)

27 Couple in the past, one exactly like another, embracing amour principally (5)

28 Luxury car crumpled on the French motorway finally (7)

 2  Islam unexpectedly accepting old language (6)

 3  Understand set up involving Kelvin's additions in Glasgow (4)

 4  Short twisting line of disorderly circle with queue now and then (8)

 5  Wild place we studied partly (4)

 6  Head, at heart hilarious old man (5)

 8  Luxurious sleeping car to attract fellow (7)

12 Hard work to insert transplanted organ (5)

14 Well-organised slumber can restore to an intelligible state (10)

16 Some of scenario tactlessly read out to mob in time of trouble (4,3)

17 Unchangeable prisoners, almost too much (8)

21 This conclusion, following start of magic, would be putting things right (6)

22 Robust, solid year (5)

24 Draw attention to plant with showy purple or yellow flowers (4)

25 Primarily hungry old US man; a vagabond (4)