Unclued lights (including one of two words) suggest a section of a sequence whose final member will appear in the completed grid and must be shaded.

Across

1 Theseus at last goes in to batter brute (5)
4 Crossed children’s author dogged by pressman (9)
9 Alkaloids exist with the smell of ale (almost) (10)
11 Head king some laird raved about (5)
12 Screech from awful person rebuffed and upset (7)
14 Positive aristo shows a prized example (5)
21 Shallow type has leak outside (8, hyphened)
22 Old statesman once closer to HM and earl (7)
24 Number on high old headland (4)
25 Colour one neglected bus shelter...