Possible Clues:

• Wheezy one
• Finding inspiration difficult, perhaps, as with recurrent idea that's lacking direction
• Bronchodilator user
• That's Mac I make out of breath
• Having difficulty finding inspiration?
• Mixture of maths at 1100 leaves one short of 11 across
• Beginning with maths, a jerk would be taking your breath away
• That's the sort of one to be breathless
• Inhaler user
• That's enough to make short of 27 down