Strange dusk gathers over uniform figures in square (6)
I believe the answer is:
sudoku
'figures in square' is the definition.
(puzzle involving squares of numbers)
'strange dusk gathers over uniform' is the wordplay.
'strange' indicates an anagram.
'gathers' means one lot of letters goes inside another.
'over' becomes 'o' (cricket abbreviation**).
'uniform' becomes 'u' (phonetic alphabet: alpha, bravo, charlie etc.).
'dusk' anagrammed gives 'sudk'.
'sudk' enclosing 'o' is 'sudok'.
'sudok'+'u'='SUDOKU'
(Other definitions for sudoku that I've seen before include "Number game" , "Numbers game" , "Numeric puzzle" , "Japanese number puzzle" , "Popular logic-based puzzle" .)