Drag peacenik off grasping ordinal (4,2,3,4)
I believe the answer is:
pain in the neck
'drag' is the definition.
(thesaurus)
'peacenik off grasping ordinal' is the wordplay.
'off' indicates anagramming the letters.
'grasping' means one lot of letters goes inside another.
'ordinal' becomes 'ninth' ('ninth' can be similar in meaning to 'ordinal').
'peacenik' is an anagram of 'paieneck'.
'paieneck' enclosing 'ninth' is 'PAIN IN THE NECK'.
(Other definitions for pain in the neck that I've seen before include "Annoyance (colloq.)" , "Very tiresome person or thing" , "Headache" , "Troublesome person or thing" , "Persistently difficult person or thing (caused by a whiplash?)" .)