Loathing is beginning to grind in the dirt (7)
I believe the answer is:
disgust
'loathing' is the definition.
(I've seen this before)
'is beginning to grind in the dirt' is the wordplay.
'beginning to' says to take the initial letters.
'in' means one lot of letters goes inside another.
'the dirt' becomes 'dust' (dust is a kind of dirt).
The initial letter of 'grind' is 'g'.
'is'+'g'='isg'
'isg' going into 'dust' is 'DISGUST'.
(Other definitions for disgust that I've seen before include "contempt" , "Strong revulsion" , "'Sicken, revolt (7)'" , "nausea" , "Nauseate" .)