Genius 211

[Unicorn5]

Stuck on the last six! I think I have the answers, but I can't parse.
1D Ocean's visor lifted now and again here? (6) C?S?N? Casino?
3D Bills to secure banker from Santander seats (10) P?S?E?I?R? Posteriors?
21D Shift uncomfortable large sums of money after US lawyer loses case (6) ?Q?I?M Squirm?
25D Poppy product's opening triad is lifted from heavy metal (5) O?I?M Opium?
10A Cast from the Beach, perhaps, had a casual read-through (7) S?I?M?D Skimmed? (Skim + Med?)
23A Power line for telephone (4) C?B? Cube? (def as in 2 to the power of 3 = 2 cubed)
This is a themed crossword as per previous threads under Genius 211.
Any help appreciated. Thanks.

[bobbinwales]

now and again could mean alternate letters oCeAnSvI to give the casio bit?

[Mamyalynne]

10a Skimmed, double def -- to skim a stone on the water and to read quickly.

[Mamyalynne]

3d Posters (Bills) round Rio (River/banker)

[bobbinwales]

21 is clue wording uncomfortablY? So thats the definition?

[Mamyalynne]

21 (E)Squir(e) - US lawyer without case + M(oney)

[herbage]

1d surely n does not represent now? I.e. alternate in oceans visor gives Casio. Insert N?

[Mamyalynne]

Instructions if they help.

In six clues their wordplay element contains surplus letters, to be ignored. In a further six clues more recent versions of each of these six letters are lacking from their wordplay.

[ProfessorMaisie]

1d - 'n' alternative letters in first two words = CASIO
3d 'bills' = 'posters' + rio = Spanish river/'banker' (humorous)
21d 'lawyer' in USA is '(e)SQUIR(e)' + M (millions$?)
25 take 3 letters (triad) from (eur)OPIUM
10 just a double def.
23 sounds like (ie 'on the telephone') 'queue' for 'line' with 'b' missing from wordplay - def 'power' in the maths sense

[Mamyalynne]

Oh, I fared better than I thought.

[Captain2]

Give yourself a pat on the back and have a cup of tea Mamya. :))))

[ProfessorMaisie]

Yes, Mamyalynne - I could have saved myself some effort there!

Just to clarify - the 'n' is missing from wordplay in 1 (CASInO) and the 'sounds like' 'line' = 'queue' = CUE gives the answer minus 'b' (CUbE)

[Unicorn5]

Thank you to all, will go back and have a look at all answers.