Badger runs and runs into grass (5)
I believe the answer is:
harry
'badger' is the definition.
(I know that badger is a kind of bedevil)
'runs and runs into grass' is the wordplay.
'runs' becomes 'r' (cricket abbreviation).
'and' is a charade indicator (letters next to each other).
'runs' becomes 'r' (cricket abbreviation).
'into' indicates putting letters inside.
'grass' becomes 'hay' (hay is dried grass).
'r' put after 'r' is 'rr'.
'rr' going within 'hay' is 'HARRY'.
(Other definitions for harry that I've seen before include "Make predatory raids" , "Torment by constant attack" , "Hector" , "Annoy continually" , "Persistently attack (an enemy)" .)