Settled matter in court, at last, after side upset team members (8)
I believe the answer is:
sediment
'settled matter' is the definition.
(I've seen this in another clue)
'court at last after side upset team members' is the wordplay.
'at last' indicates one should take the final letters.
'after' says to put letters next to each other.
'upset' is an anagram indicator.
'team members' becomes 'men' (I can't justify this - if you can you should believe this answer much more).
The final letter of 'court' is 't'.
'side' anagrammed gives 'sedi'.
'sedi'+'men'='sedimen'
't' put after 'sedimen' is 'SEDIMENT'.
'in' is the link.
Can you help me to learn more?
(Other definitions for sediment that I've seen before include "Matter settling (on seabed)" , "Matter settling out in fluids" , "Lees" , "Material settling out in a liquid" , "Particles that settle on the bottom of river or wine" .)