Old-fashioned occupation duke summarised (8)
I believe the answer is:
outlined
'summarised' is the definition.
(I've seen this in another clue)
'old-fashioned occupation duke' is the wordplay.
'old-fashioned' becomes 'out' (as opposed to 'in').
'occupation' becomes 'line' (line can mean someone's occupation or industry).
'duke' becomes 'd' (abbreviation).
'out'+'line'+'d'='OUTLINED'
(Other definitions for outlined that I've seen before include "Described roughly or briefly" , "Traced" , "Gave summary of chief facts - drew them?" , "Sketched, described briefly" .)