Having possessions, duke put on appropriate neckwear (10)
I believe the answer is:
propertied
'having possessions' is the definition.
(having property)
'duke put on appropriate neckwear' is the wordplay.
'duke' becomes 'd' (abbreviation).
'put on' means one lot of letters go next to another (some letters go on or after others).
'appropriate' becomes 'proper' (similar in meaning).
'neckwear' becomes 'tie' (type of neckwear).
'proper'+'tie'='propertie'
'd' put after 'propertie' is 'PROPERTIED'.
(Other definitions for propertied that I've seen before include "Owning houses" , "Having premises" , "Owning buildings and land" , "Landed" .)