Learn Russian: Она достаточно хитра, чтобы избежать скандала. - She is cunning enough to avoid a scandal.

In English, we say "cunning enough to avoid," linking the phrase directly to an infinitive. Russian doesn't allow this direct link. To express the result of being "sufficiently" or "too" something, you must use a subordinate clause introduced by чтобы. You are literally saying, "She is sufficiently cunning, in order to avoid a scandal."

Why does the sentence use the short form хитра instead of the full form хитрая?

While Она достаточно хитрая... is grammatically possible in colloquial speech, short-form adjectives (like хитра) are strongly preferred when acting as the main predicate of a sentence alongside degree adverbs like достаточно (enough) and слишком (too). It sounds much more natural and slightly more formal.

Why is скандал in the Genitive case (скандала) instead of the Accusative?

The verb избежать (to avoid) strictly requires its object to be in the Genitive case. You can think of it conceptually as "escaping from a scandal." As a handy rule of thumb, many Russian verbs with the prefix из- or verbs implying separation, fear, or deprivation take the Genitive.

Could we use the imperfective избегать here instead of избежать?

It wouldn't fit the likely meaning. The perfective избежать is used here because it refers to successfully avoiding one specific, impending scandal. If you used the imperfective избегать, it would imply a general, repeated habit: "She is cunning enough to always avoid scandals."