The same word appears as seven headwords in Chambers. Unclued lights (including two pairs and one of three words, one of two) indicate the meaning of six of them. The word (4) will appear in the completed grid and must be shaded.

Across

9 Half-dead ryot’s thirsty (4)
11 Fit PM adopts Latin not a little (10)
14 Tiring trek from Jamaica by cat less ordinary (6)
17 Very laid back mature Amerind (5)
18 Discoloured hat shared by half a dozen (5)
20 Japanese art school, one following old watercolourist (7)
21 Let outside, Paul (not inside) limped (7)
23 Movement Jack Sprat embraces (7)
25 Lady C cycling,...