Rubbish talk doesn't finish with fellows (5)
I believe the answer is:
chaff
'rubbish' is the definition.
(I've seen this in another clue)
'talk doesn't finish with fellows' is the wordplay.
'talk' becomes 'chat' (chat can mean to talk).
'doesn't finish' means to remove the last letter.
'with' says to put letters next to each other.
'fellows' becomes 'ff' (an abbreviation for fellow written twice).
'chat' with its final letter removed is 'cha'.
'cha'+'ff'='CHAFF'
(Other definitions for chaff that I've seen before include "Light banter - husks from corn" , "Shucks" , "Refuse - banter" , "something worth little" , "Worthless material (from corn)" .)