Tiles hopefully all toppling in old cupola’s nets (8)
I believe the answer is:
dominoes
'tiles hopefully all toppling' is the definition.
I can't judge whether this definition defines the answer.
'in old cupola's nets' is the wordplay.
'old' becomes 'o' (abbreviation).
'cupola's' becomes 'dome's' (architectural term).
'nets' is an insertion indicator (some letters are contained or netted).
'in'+'o'='ino'
'ino' placed within 'domes' is 'DOMINOES'.
Can you help me to learn more?
(Other definitions for dominoes that I've seen before include "Number-matching game" , "Mistakes" , "Table-top game" , "Traditional pub game" , "Game played with black pieces with white spots" .)