Detest swearing in case of ladette (6)
I believe the answer is:
loathe
'detest' is the definition.
(loathing is a kind of detesting)
'swearing in case of ladette' is the wordplay.
'swearing' becomes 'oath' ('oath' can be a synonym of 'swearing').
'in' indicates putting letters inside.
'case of' suggests removing the centre (outsides of).
'ladette' with its centre taken out is 'le'.
'oath' going into 'le' is 'LOATHE'.
(Other definitions for loathe that I've seen before include "Find disgusting" , "cannot stand" , "Abhor, detest" , "Can't stand" , "Feel disgust for (person)" .)