Cold cut, ultimately very tough (5)
I believe the answer is:
chewy
'tough' is the definition.
(similar in meaning)
'cold cut ultimately very' is the wordplay.
'cold' becomes 'C' (eg on taps).
'cut' becomes 'hew' (hew can mean to chop or cut).
'ultimately' indicates one should take the final letters.
The last letter of 'very' is 'y'.
'c'+'hew'+'y'='CHEWY'
(Other definitions for chewy that I've seen before include "Soft and sticky (to eat)" , "Taking much mastication" , "Tough to masticate" , "Requiring mastication, like toffee say" , "With a texture like toffee" .)