Resort to row, initially, and quarrel (4)
I believe the answer is:
spar
'quarrel' is the definition.
(I've seen this before)
'resort to row initially' is the wordplay.
'resort' becomes 'spa' (spa is a kind of resort).
'to' means one lot of letters go next to another.
'initially' says to take the initial letters.
The first letter of 'row' is 'r'.
'spa'+'r'='SPAR'
'and' acts as a link.
(Other definitions for spar that I've seen before include "Shadow box" , "quarrel" , "Shadow-box" , "Pole used in rigging - fight" , "Sticks" .)