Badger runs repeatedly into grass (5)
I believe the answer is:
harry
'badger' is the definition.
(thesaurus)
'runs repeatedly into grass' is the wordplay.
'runs' becomes 'r' (cricket abbreviation).
'repeatedly' indicates the doubling of some letters.
'into' indicates putting letters inside.
'grass' becomes 'hay' (I have seen 'Mown grass ' mean 'hay' so perhaps 'grass' could also mean 'hay'**).
'r' duplicated is 'rr'.
'rr' placed within 'hay' is 'HARRY'.
(Other definitions for harry that I've seen before include "Torment by constant attack" , "Annoy continually" , "Ravage - pester" , "Persistently harass" , "Make predatory raids" .)