Five unclued Across lights are of a kind and are out of place as the five unclued Down lights.

        Across

   1    Thinly scattered food chain outside of Stevenage (6)

   7    Place in complete shade (6)

13    Multitude of fishes on sandbank (5)

15    Fruit ain’t green when squeezed (9)

20    Fruit and nut salad ordered, without dressing, to start with (7)

21    Paper money returned for eating apple (6)

22    Barrow-boy arranged escort (6)

24    Chatty comedian arrives next to new canal (4,4)

26    Old solver is second person in the OT (4)

27    Neeson regularly appearing in Keanu’s role (3)

28    In short, especially.