Strip of material the German brought over was narrower at one end (7)
I believe the answer is:
tapered
'narrower at one end' is the definition.
(I've seen this before)
'strip of material the german brought over' is the wordplay.
'strip of material' becomes 'tape' (I am not sure about this - if you are sure you should believe this answer much more).
'the german' becomes 'der' ('the' in German).
'brought over' says the letters should be written in reverse.
'der' back-to-front is 'red'.
'tape'+'red'='TAPERED'
'was' acts as a link.
Can you help me to learn more?
(Other definitions for tapered that I've seen before include "Narrowed by red tape" , "Predate (anag)" , "Became gradually narrower as candle may" , "Pointed" , "Narrowing towards one end" .)