Dull brown, new-age material found in ship's hold (7)
I believe the answer is:
dunnage
'material found in ship's hold' is the definition.
'dull brown new-age' is the wordplay.
'dull brown' becomes 'dun' (I've seen this in another clue).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'dun'+'n'+'age'='DUNNAGE'
(Other definitions for dunnage that I've seen before include "Loose material for packing cargo" , "Anne dug (anag) - sailor's baggage" .)