The unclued Across lights were of a kind, as are the unclued Down lights now. All are verifiable in Brewer under 16.

Across

4    Team go over to Irish monument (6,5)
11    Train pass daughter’s lost (7)
12    Delicate and light, keeping in time (6)
13    Colluding with ancient tribe’s hilarious escapades (2,7)
19    Band’s origin (7)
21    Get together in time-share (4)
23    Milky tea, call for change (7)
25    Chatterbox not quiet – noisy type (7)
32    1980s Austin model having some art form (7)
34    Could be Dover – or not! (4)
35    Sapper composed unfinished Mass – one for the dead (7)
40    Number eating large meal (5)
41    Two-thirds...