Intense and irrational fear (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
phobia
(Other definitions for phobia that I've seen before include "Overpowering fear" , "Irrational fear of something" , "Anxiety disorder" , "A lasting abnormal fear of smoething" , "An irrational fear or dislike" .)