From Longman Dictionary of Contemporary Englishburning issue/questionburning issue/questiona burning issue or question is very important and urgent Education has become a burning issue in this election. → burning
Examples from the Corpus
burning issue/question• The star trek is over for today, but the burning questions are still unanswered.• Quality, of design and typography rather than editorial matter, is a burning issue as far as desktop publishing is concerned.• Transmission has always been the burning issue for scientists interested in studying this epidemic.• But the burning question is: How many times a day do kids wander in looking to buy rolling papers?• The burning question is - how soon?• Another burning issue is unfair dismissal.• It can also lead to the efficacy of our advice becoming the burning issue of discussion. 