The first man seen by a duke in the morning (4)
I believe the answer is:
adam
'the first man' is the definition.
(first man in the Bible)
'by a duke in the morning' is the wordplay.
'by' says to put letters next to each other.
'duke' becomes 'd' (abbreviation).
'in the morning' becomes 'am' (short for ante meridiem - before noon).
'a' put next to 'd' is 'ad'.
'ad'+'am'='ADAM'
'seen' acts as a link.
(Other definitions for adam that I've seen before include "who transformed the Palladian style?" , "__ Smith, author of The Wealth of Nations" , "man expelled from garden" , "neoclassical style" , "the first orphan?" .)