Where nail may be caught, getting pulled (2,3)
I believe the answer is:
on tow
'getting pulled' is the definition.
(on tow means being pulled along)
I don't understand the rest of the clue.
(Other definitions for on tow that I've seen before include "A caravan is usually" , "Being drawn" , "Being pulled along" , "being strung along?" , "being pulled by trucker?" .)