A carrier bearing building materials westward to Gulf metropolis (4)
I believe the answer is:
doha
'gulf metropolis' is the definition.
The definition and answer can be both locations as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'a carrier bearing building materials westward' is the wordplay.
I cannot quite see how this works, but
'a' is within the answer.
The remaining letters 'doh' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
'to' is the link.
Can you help me to learn more?
(Other definitions for doha that I've seen before include "Capital of Qatar" , "Trade round" , "Gulf resort" .)