An old bag in a carriage (9)
I believe the answer is:
gladstone
'bag in a carriage' is the definition.
'Gladstone' can be an answer for 'bag' (Gladstone is an example). I'm not certain of the 'in a carriage' bit.
'an old' is the wordplay.
I cannot really see how this works, but
'an' could be 'one' and 'one' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for gladstone that I've seen before include "Politician" , "Old English P.M. or a doctor's bag" , "19th-century prime minister" , "Former British prime minister and large travelling bag" , "Victorian GOM" .)