Bride's upset by all this rubbish (6)
I believe the answer is:
debris
'all this rubbish' is the definition.
'debris' can be an answer for 'rubbish' (debris is a kind of rubbish). I'm not certain of the rest of the definition.
'bride's upset' is the wordplay.
'upset' indicates an anagram.
'brides' is an anagram of 'DEBRIS'.
'by' acts as a link.
Can you help me to learn more?
(Other definitions for debris that I've seen before include "Detritus, rubbish" , "Brides with pieces of rubble" , "Rubble, lots of broken pieces" , "Rubble, detritus" , "Fragments of rubbish" .)