Dispute and squabble for Cock Robin's killer (7)
I believe the answer is:
sparrow
'cock robin's killer' is the definition.
(I've seen this before)
'dispute and squabble' is the wordplay.
'dispute' becomes 'spar' (I've seen this before).
'and' means one lot of letters go next to another.
'squabble' becomes 'row' (I've seen this in other clues).
'spar'+'row'='SPARROW'
'for' is the link.
(Other definitions for sparrow that I've seen before include "Common small bird" , "one on the wing" , "fowl, using outdated term" , "Cock Robin's killer" , "Small brownish bird" .)