Cut up roast, initially restricted by word of warning (5)
I believe the answer is:
carve
'cut up' is the definition.
(I know that cut up can be written as carve)
'roast initially restricted by word of warning' is the wordplay.
'initially' says to take the initial letters.
'restricted by' is an insertion indicator (inserted letters are restricted or trapped).
'word of warning' becomes 'cave' (old-fashioned term meaning 'look out!').
The initial letter of 'roast' is 'r'.
'r' put into 'cave' is 'CARVE'.
(Other definitions for carve that I've seen before include "fashion" , "Chisel, sculpt" , "Slice (joint)" , "Cut meat into slices for eating" , "Cut (cooked meat)" .)