Thousand fine varieties are cut (5)
I believe the answer is:
knife
'are cut' is the definition.
(I've seen this before)
'thousand fine varieties' is the wordplay.
'thousand' becomes 'K' (synonyms).
'varieties' indicates anagramming the letters (I've seen 'variety' mean this).
'fine' anagrammed gives 'nife'.
'k'+'nife'='KNIFE'
(Other definitions for knife that I've seen before include "Cutting blade" , "following Stanley perhaps" , "Cutting instrument" , "Cutting utensil" , "Cutlery item" .)