Cut rodents besetting bottom of garden (5)
I believe the answer is:
mince
'cut' is the definition.
(thesaurus)
'rodents besetting bottom of garden' is the wordplay.
'rodents' becomes 'mice' (mouse is a kind of rodent**).
'besetting' is an insertion indicator.
'bottom of' says to take the final letters.
The final letter of 'garden' is 'n'.
'mice' placed around 'n' is 'MINCE'.
(Other definitions for mince that I've seen before include "meat in small portions" , "Chop food into small bits" , "Diced meat" , "Cut meat into small pieces, or walk affectedly" , "Chop into small pieces" .)