The first man to cause a lady to lose her head (4)
I believe the answer is:
adam
'the first man' is the definition.
(first man in the Bible)
'lady to lose her head' is the wordplay.
I cannot quite understand how this works, but
'lady' could be 'ada' and 'ada' is located in the answer.
A single letter 'm' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
'to cause a' is the link.
Can you help me to learn more?
(Other definitions for adam that I've seen before include "Eden inhabitant" , "First Christian ancestor" , "Male" , "Robert -, Sc. architect" , "Father of man" .)