Run one? (4)
I believe the answer is:
race
'run one?' is the definition.
'race' can be an answer for 'run' (synonyms). I am not sure about the 'one?' bit.
'run one?' is the wordplay.
'run' becomes 'r' (cricket abbreviation).
'one?' becomes 'ace' (ace has a value of one in some card games).
'r'+'ace'='RACE'
(Other definitions for race that I've seen before include "Running contest" , "Stock" , "Run; nation" , "put their skates on" , "Care about contest" .)