Jurisprudence needs new turf (4)
I believe the answer is:
lawn
'turf' is the definition.
(thesaurus)
'jurisprudence needs new' is the wordplay.
'jurisprudence' becomes 'law' (synonyms).
'needs' is a charade indicator (letters next to each other).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'law'+'n'='LAWN'
(Other definitions for lawn that I've seen before include "Grassy area" , "material" , "Area of tended grass" , "Grassy patch" , "Green area" .)