Requires a cutting edge alloy of potassium, nickel and iron (5)
I believe the answer is:
knife
'requires a cutting edge alloy' is the definition.
I can't tell whether this definition defines the answer.
'potassium nickel and iron' is the wordplay.
'potassium' becomes 'K' (K is the chemical symbol for potassium).
'nickel' becomes 'Ni' (Ni is the chemical symbol for nickel).
'and' says to put letters next to each other.
'iron' becomes 'Fe' (chemical symbol for iron).
'k'+'ni'+'fe'='KNIFE'
'of' is the link.
Can you help me to learn more?
(Other definitions for knife that I've seen before include "Table implement" , "following Stanley perhaps" , "Lethal weapon" , "Cutting instrument" , "Edge tool" .)