```json
{
  "no": ["no"],
  "yes": ["yes"]
}
```

Based on the feature description, the "default" feature has only two possible values: "no" and "yes". It is unclear how the "default" feature is related to the target variable, but we can assume that if the client has credit in default (value: "yes"), there is a higher possibility that the client will not subscribe to a term deposit (target class: "no"). Similarly, if the client does not have credit in default (value: "no"), there is a higher possibility that the client will subscribe to a term deposit (target class: "yes").

In the provided dictionary, the key "no" represents the target class "no" (client not subscribing to a term deposit), and the corresponding value is ["no"], indicating that in this target class, the only possible value for the "default" feature is "no". Similarly, the key "yes" represents the target class "yes" (client subscribing to a term deposit), and the corresponding value is ["yes"], indicating that in this target class, the only possible value for the "default" feature is "yes".

Please note that it is assumed that there are no other undefined or unlisted values for the "default" feature.