To sound intelligent on political issues is an infinitive phrase that functions as a noun and the subject in the sentence. The verb sound is a linking verb in the infinitive phrase, that is why the adjective intelligent is not a complement of this verb. So, there is no overt subject for the infinitive phrase in the sentence and the adjective *intelligent"intelligent can't be an overt complement of anything in the sentence. But, if we rearrange the sentence in for counstruction, It is a goal for Wayne to sound intelligent on political issues , it is possible to understand that the adjective intelligent is a so called implied complement of the noun Wayne in the possessive in the infinitive phrase to sound intelligent on political issues in the sentence. Or, the adjective intelligent is a complement by implication of the word Wayne.