Building stone at last provided in numbered blocks? (7)
I believe the answer is:
edifice
'building' is the definition.
(I know that building can be written as edifice)
'stone at last provided in numbered blocks?' is the wordplay.
'at last' says to take the final letters.
'provided' becomes 'if' (eg 'provided it's sunny' means 'if it's sunny').
'in' means one lot of letters goes inside another.
'numbered blocks?' becomes 'dice' (dice are blocks with numbers on them).
The last letter of 'stone' is 'e'.
'if' going within 'dice' is 'difice'.
'e'+'difice'='EDIFICE'
(Other definitions for edifice that I've seen before include "impressive pile!" , "Grand building" , "Construction" , "Fine building" , "Large structure" .)