Six unclued lights (one hyphened) suggest words each differently formed from the same 13 22, which appears as a clued light and must be shaded.#
 

Across

 
1    Common choir dressed in black and white (11)
11    Thing every elder has about yellow waistcoat (6)
15    Message in letter about this month in Paris? (5)
16    Bard’s encounter in narrow passage (5)
17    Trumpet introduces king and queen – I lie in wait (6)
18    Posh man in warship (5, hyphened)
20    Pothead strong individual curbed (6)
21    Morose and without doubt lacking in energy (5)
27    African ruler hid a misguided prophet (7)
29    Tons o’ bananas beasts of burden humped...