The unclued entries (two of one word, two of two words, two of three words) combine to form a quotation. Elsewhere, ignore two accents.

        Across

   1    Promotions to fix in commercial vehicles (12)

10    Eager pupil’s plea for online phenomenon (4)

12    Cockney dish rose, having turned end (3,1,4,2)

14    Remark further problem with concentration (3)

15    Angler uses this weight in river, they say (8)

17    Gold cloth piece is not silver – this might be either (5)

18    Win back billion, not having a scale again (7)

19    Understanding one? (6)

22    Analog ____ could be ‘slo-mo’, managed badly? (6)

24    A state surrounded by empty sea...