Expensive habit that's seen at dinner? (5,3)
I believe the answer is:
black tie
'expensive habit' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'that's seen at dinner?' is the wordplay.
I cannot quite see how this works, but
'that's' could be 'ie' and 'ie' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for black tie that I've seen before include "Formal attire" , "One accompanies DJ" , "Formal (neck)wear" , "expensive party-going habit" , "Formal evening dress for men" .)