Sort of races requiring lots of land (5)
I believe the answer is:
acres
'lots of land' is the definition.
(I've seen this in another clue)
'sort of races' is the wordplay.
'sort of' is an anagram indicator.
'races' is an anagram of 'ACRES'.
'requiring' acts as a link.
(Other definitions for acres that I've seen before include "lots" , "may burden landed folk" , "Rival played" , "farmland maybe?" , "fields?" .)