The unclued lights appeared at the start under the shaded squares reading row by row from top to bottom (two words).

Across

5 Touring hotel, arrive at poor area (6)

10 Old driver will show support going about in revelry (10)

12 Resort with edge beside popular island (6)

16 Church collection on foot? (5)

17 Unfortunately lacks ID of northern bards (7)

18 Decide to answer a clue again (7)

20 Chips in, holding a dairy cow (8)

25 Prasanna captures Ethiopian prince and headland (3)

26 Spring holiday with least to offer (7)

28 41C involved Inverse function...