2126: Word building

The unclued lights can be arranged into a chain of anagrams of 3 to 11 letters in length, with the addition of one letter step by step.
 

Across

7 Towboat capsized in channel (3)
11 Contain grease once (6)
13 Against work — was perplexed (7)
15 Bender on river (5)
16 Two flowers of sorts in colleges (5)
17 Prudently state diocese (6)
20 Hymn to alluring female without power (6)
21 Associated feature that is in the can (5, hyphened)
27 Artificial swap of Mafia member (7, hyphened)
29 Warm-up races! (5)
30 One hug could become sufficient (6)
32 Great desire of ogre, edified (5)
34 Herbie’s mallet for game (6)
36 Japanese artist’s black structure (5)
37 Broadcasting with Grace — but not young Deborah (5, two words) …
38 … which is involved with one final state (7)
39 Cobras not swimming horizontally (6)
41 Flier on ledge — gale-tossed (11, two words)
 

Down

1 Measuring system troubled two year crew (11, two words)
2 Fitting old question about appeal (8)
3 Stores in pits with lines arranged for a long time (9)
4 Popular compiler, I natter about train (12)
5 Close, holding flower, at Hogmanay? (7, two words)
6 Poem translated by Norden’s partner, upset mart (8)
7 Shrub two Democrats removed from bardic meeting (5)
9 Dad lifted instrument losing nothing. That’s the way in Italy (6)
10 Computing device, popular style mouse at first (5)
12 Arouse top industrialist opening sixth of factories (6)
14 Member of RC faction edited rotten manual (12)
24 Choral work — quiet, but not folk (8, hyphened)
26 Torment old Oxbridge official around six (7)
28 He ordered ‘No Deal’ (6)
31 Composer from Hungary tailed New Zealander (5)
33 Criticise joint (5)
35 Go and visit Midland river, topless (4)
 
A first prize of £30 for the first correct solution opened on 2 September. There are two runners-up prizes of £20 (or, for UK solvers, the latest edition of The Chambers Dictionary — ring the word ‘Dictionary’).