Rows of pigs with no head (4)
I believe the answer is:
oars
'rows' is the definition.
(I've seen this before)
'pigs with no head' is the wordplay.
'pigs' becomes 'boars' (I have seen 'Male pigs' mean 'boars' so perhaps 'pigs' could also mean 'boars').
'with no head' means to remove the first letter.
'boars' with its initial letter taken away is 'OARS'.
'of' is the link.
(Other definitions for oars that I've seen before include "Manually operated boat propellers" , "Poles to propel a boat" , "Busy bodies usually stick them in, also used in rowing" , "Boating implements" , "Rowing blades" .)