Quarrels can get endlessly worse! (4)
I believe the answer is:
rows
'quarrels' is the definition.
('row' can be a synonym of 'quarrel')
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for rows that I've seen before include "Arguments" , "emotional exchanges" , "Tiers" , "Rackets" , "Columns" .)