He makes a list of bequests at one in the morning (7)
I believe the answer is:
william
'he' is the definition.
'a list of bequests at one in the morning' is the wordplay.
'a list of bequests' becomes 'will' (list of bequests given after someone's death).
'at' says to put letters next to each other.
'one in the morning' becomes 'Iam' (1am).
'will'+'iam'='WILLIAM'
'makes' is the link.
(Other definitions for william that I've seen before include "Prince Harry's brother" , "Shakespeare or Pitt, say" , "See 20" , "Boy's name" , "Bill" .)