It's silly to get involved in an endless dispute (6)
I believe the answer is:
stupid
'it's silly' is the definition.
(I've seen this before)
'involved in an endless dispute' is the wordplay.
'involved in' is an anagram indicator (involved can mean complex or confusing).
'an endless' means to remove the last letter.
'dispute' with its last letter taken away is 'disput'.
'disput' with letters rearranged gives 'STUPID'.
'to get' is the link.
(Other definitions for stupid that I've seen before include "Idiot" , "Dull" , "Asinine" , "bovine" , "moronic" .)