It has the edge if Ken is involved (5)
I believe the answer is:
knife
'it has the edge' is the definition.
The definition suggests a singular noun which matches the answer.
'if ken is involved' is the wordplay.
'is involved' indicates anagramming the letters (involved can mean confusing or complex).
'if'+'ken'='ifken'
'ifken' is an anagram of 'KNIFE'.
Can you help me to learn more?
(Other definitions for knife that I've seen before include "Cut" , "Piece of cutlery" , "Cutting implement - stab" , "following Stanley perhaps" , "Cutting tool" .)