A piece of cake (4)
I believe this is a double definition.
'a piece' is the first definition.
(I have seen 'Piece of paving' mean 'slab' so perhaps 'piece' could also mean 'slab')
'cake?' is the second definition.
(thesaurus)
'of' acts as a link.
(Other definitions for slab that I've seen before include "24 tinnies [STRINE] < in a wooden hut [STRINE]" , "Flat mass of stone" , "Large block of stone or concrete" , "Hunk" , "Mortuary table" .)
'a piece of cake' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for easy that I've seen before include "Obliging; go carefully" , "Simple (like the living in 1 across)" , "Achieved without effort" , "Not challenging" , "Comparable to pie?" .)
'a piece of cake' is the definition.
(both can mean something very easy)
This is all the clue.
(Other definitions for cinch that I've seen before include "Something easily done" , "In slang, a certainty or easy task" , "piece of cake" , "A walk in the park" , "simple job" .)
'a piece of cake' is the definition.
(both can mean something very easy)
This is the entire clue.
(Other definitions for doddle that I've seen before include "Something easily done" , "Absurdly simple" , "In slang, an easy task" , "Piece of cake" , "Easy crossword?" .)