With a cutting edge, youth pierces couch (6)
I believe the answer is:
bladed
'with a cutting edge youth pierces couch' is the definition.
I can't tell whether this definition defines the answer.
'youth pierces couch' is the wordplay.
'youth' becomes 'lad' (lad means a young man).
'pierces' means one lot of letters goes inside another (some letters pierce a hole in others).
'couch' becomes 'bed' (I've seen this before).
'lad' placed within 'bed' is 'BLADED'.
Can you help me to learn more?
(Another definition for bladed that I've seen is " Like oars".)