From Longman Dictionary of Contemporary Englishawkward/tricky/tough etc customerawkward/tricky/tough etc customerHELPsomeone who is difficult to deal with because they behave in a deliberately unhelpful way → cool customer at cool1(3) → customer
Examples from the Corpus
awkward/tricky/tough etc customer• He looks a tough customer to deal with.• A tough customer, a man to be reckoned with.• But the tough treatment was only for tough customers.• He's overcome some genuinely tough customers, but Gimenez was abject.• But he'd take on some one like Glenda Grower, who's a much tougher customer.• The next, you're making speeches to the wind. Tricky customers, ordinary people. 