Obligation to pursue brass accessory (7)
I believe the answer is:
necktie
'accessory' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?
'obligation to pursue brass' is the wordplay.
'obligation' becomes 'tie' (I've seen this before).
'to pursue' means one lot of letters go next to another.
'brass' becomes 'neck' (both can mean insolence).
'tie' after 'neck' is 'NECKTIE'.
Can you help me to learn more?
(Other definitions for necktie that I've seen before include "What Yank may wear" , "this'll go with shirt" , "Ascot?" , "clothing accessory from America" , "Formal wear" .)