The unclued lights (three of two words) are of a kind.
 

Across

1    Slices top of sausage in front of dogs (5)
6    Starting at Keele, say, in flames? (7, two words)
11    Former England captain has Alec Robins out (10, two words)
15    Heartless Valentine’s streamer (4)
17    Wild chatter has teeth on edge (7)
18    Drink Church of Scotland finally banned (3)
21    Matches for Spurs and the Hammers say (5)
24    Peterborough’s backed some network (4)
27    Spanish province drops green knitwear (4)
28    A hospital covered by me, just for now (5, two words)
33    City replay regularly (3)
35    Potentially profitable project is yours for ten, as...