X is a shared definition. Any unfamiliar words may be found in Chambers 12th edition
Across
l State agree to have right for name (6) 5 Building material argument against island (8) 9 Prison with second offenders 10 Guarantee Cerberus never holds back? (6) 11 Poorly runners might hit this eccentric (3-3-4) 12 Truss’s intractable problem? (4) 13 Construction worker’s requirement to dress down, entertaining a couple of females (8) 16 Pontificate about end of winter showing new growth (6) 17 X’s disturbed dreams, mostly about the origin of life (6) 19 Sinatra’s song about class and stars (5,3) 21 X’s existence with a change of gender (4) 22 X is unable to before a glass (10) 25 Avoid responsibility with firm expression of petulance (3,3) 26 What may be used to describe orbits (8) 27 Crew died, regrettably, for such universal symbols (8) 28 The rest of the day? (6)