tough nut to crack

a tough nut

A person, thing, situation, or problem that is particularly difficult to understand, solve, or deal with. I've been dating Jenny for over a year, and I still think she's a tough nut to crack! Figuring out the best way to modernize our product without alienating existing customers is definitely a tough nut to crack. The spy we captured is a tough nut; he hasn't said a thing since we began the interrogation.
See also: nut, tough

tough nut to crack

verb
See also: crack, nut, tough
References in classic literature ?
He tries this on very much with me, but I flatter myself he has got a tough nut to crack.
However, if we can go down there and be at our best then we'll be a tough nut to crack.
15) stamped his class on the card and looks tough nut to crack with Galway in mind.
Pradera has been in operation for more than a year now and is one tough nut to crack when the winds blow.
Rebecca Menzies-trained Halycon Days proved a tough nut to crack and saw off Supreme Asset by a neck in the two-mile handicap chase.
ALAN PARDEW is looking forward to pitting his wits against Sam Allardyce tomorrow - but has warned that his old adversaries Sunderland will be a tough nut to crack.
However, he has far less on his plate, and with conditions to suit, he should be a tough nut to crack.
The Sunset Strip in West Hollywood, a mecca for tourists, has nevertheless proven a tough nut to crack for restaurateurs.
Favourite Prince Gibraltar, an unlucky-in-running third in the French Derby, looked to have all bases covered but found first Teletext a tough nut to crack before Gallante hit another gear in the Derrick Smith colours to foil Jean-Claude Rouget's hotpot.
India, June 10 -- Apple has signed a deal with Sony Music Entertainment, the major label that had remained a tough nut to crack all these months, for the much anticipated iRadio service.
Dudley boss Will Pottinger, meanwhile, says Coventry Storm will be a tough nut to crack when the rivals meet at Monmore on Tuesday.
Ali Al Asfoor found Ali Dhawani a tough nut to crack before scoring a 7-5, 6-3 victory, while Ahmed Mohammed Rasool beat Hussain Dhawani 6-1, 6-4.
Libya have a tough nut to crack Tuesday if they are to reach the final of the 9th Arab Nations Cup as they will be meeting hosts Saudi Arabia as the the runners-up with the highest score in the group matches.
But league newcomers Lido will prove a tough nut to crack having lost just once in nine outings to surge clear of the basement zone.