Clear end of day without question revealing quickness of thought (6)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

Clear end of day without question, revealing quickness of thought AC <q> UIT (=clear, exonerate, in court; “without question (=Q, as in Q&A)” means letter “q” is dropped) + <da> Y (“end of” means last letter only)