Supported you and me in marked exterior (9)
I believe the answer is:
sustained
'supported' is the definition.
('sustain' can be a synonym of 'support')
'you and me in marked exterior' is the wordplay.
'you and me' becomes 'us' (the two of us).
'in marked' becomes 'stained' (I've seen this before. I am not sure about the 'in' bit.).
'exterior' indicates putting letters inside (some letters go on the outside of others).
'us' put within 'stained' is 'SUSTAINED'.
Can you help me to learn more?
(Other definitions for sustained that I've seen before include "held up" , "Steady" , "Long drawn-out" , "bore" , "Kept going, supported" .)