Trudge back to get party record (4)
I believe the answer is:
plod
'trudge' is the definition.
(I know that trudge can be written as plod)
'back to get party record' is the wordplay.
'back' says the letters should be written backwards.
'to get' says to put letters next to each other.
'party' becomes 'do' (do can informally mean a party).
'record' becomes 'L-P' (abbreviation for long play record).
'do'+'lp' is 'dolp'.
'dolp' back-to-front is 'PLOD'.
(Other definitions for plod that I've seen before include "Policeman - walk slowly" , "Walk heavily and wearily" , "Walk doggedly" , "Trudge wearily" , "Walk with effort" .)