Spot duke with yen to get off (5)
I believe the answer is:
seedy
'off' is the definition.
(I've seen this before)
'spot duke with yen' is the wordplay.
'spot' becomes 'see' (both can mean to notice or observe).
'duke' becomes 'd' (abbreviation).
'with' says to put letters next to each other.
'yen' becomes 'y' (resembles the symbol for the currency of Japan).
'see'+'d'+'y'='SEEDY'
'to get' is the link.
(Other definitions for seedy that I've seen before include "Run-down, squalid" , "Dilapidated" , "Nasty and squalid" , "Sordid and disreputable" , "Shabby and a bit dubious" .)