Barrel in bar area shows domed structure (7)
I believe the answer is:
rotunda
'structure' is the definition.
(rotunda is a kind of structure)
'barrel in bar area shows domed' is the wordplay.
I cannot quite understand how this works, but
'barrel' could be 'tun' (tun is a kind of barrel) and 'tun' is located in the answer.
'bar' could be 'rod' (both can mean a pole or stick) and 'rod' is found in the leftover letters.
'area' could be 'a' (maths abbreviation) and 'a' is present in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for rotunda that I've seen before include "Round domed building" , "Circular room or building" , "Italian Pantheon, for instance" , "Circular building with a dome" , "Do a turn (anag) -- circular domed building" .)