It's hard to get one run ahead (4)
I believe the answer is:
iron
'it's hard' is the definition.
(thesaurus)
'get one run ahead' is the wordplay.
'get' is a charade indicator (letters next to each other).
'one' becomes 'i' (Roman numeral).
'run' becomes 'r' (cricket abbreviation).
'ahead' becomes 'on' ('on' can be a synonym of 'ahead').
'i' next to 'r' is 'ir'.
'ir'+'on'='IRON'
'to' is the link.
(Other definitions for iron that I've seen before include "used in the evening" , "Fe - golf club" , "Decrease" , "Very robust" , "Flatten; element" .)