Start leading the field (3)
I believe the answer is:
lea
'the field' is the definition.
(lea can mean a meadow or field of grass)
'start leading' is the wordplay.
'start' means to remove the last letter (I've seen 'start of' mean this).
'leading' becomes 'lead' (synonyms).
'lead' with its final letter taken off is 'LEA'.
(Other definitions for lea that I've seen before include "Poetically, a piece of meadow or pasture" , "Open area of grassy or arable land" , "Tract of pastureland" , "area of grassland" , "authority for teachers" .)