Brown cloth backing exterior of elaborate material (8)
I believe the answer is:
dungaree
'material' is the definition.
(dungaree is a kind of material)
'brown cloth backing exterior of elaborate' is the wordplay.
'brown' becomes 'dun' (dun is a kind of brown).
'cloth backing' becomes 'gar' (I can't explain this - if you can you should give a lot more credence to this answer).
'exterior of' means to remove the middle letters.
'elaborate' with its centre taken out is 'ee'.
'dun'+'gar'+'ee'='DUNGAREE'
Can you help me to learn more?
(Other definitions for dungaree that I've seen before include "Cotton fabric used for overalls etc" , "fabric for clothes" .)