He has a girl at Maidenhead (4)
I believe the answer is:
adam
'he' is the definition.
'a girl at maidenhead' is the wordplay.
'a girl' becomes 'ada' (**).
'at' says to put letters next to each other.
'maidenhead' becomes 'm' (head letter of 'maiden').
'ada'+'m'='ADAM'
'has' acts as a link.
(Other definitions for adam that I've seen before include "First guy" , "First man in the Bible" , "Father of Cain and Abel" , "One of our common ancestors?" , "Robert ..., ... Clayton" .)