See face of lunatic that slays me (3)
I believe the answer is:
lol
'slays me' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.
'see face of lunatic' is the wordplay.
'see' becomes 'lo' (archaic exclamation meaning 'look!').
'face of' indicates taking the first letters.
The initial letter of 'lunatic' is 'l'.
'lo'+'l'='LOL'
'that' acts as a link.
Can you help me to learn more?
(Other definitions for lol that I've seen before include "so funny online!" , "Very funny (1)" .)