Santa's disgusting habit - poor reaction to getting stuck in chimney? (14)
I believe the answer is:
claustrophobia
'reaction to getting stuck in chimney?' is the definition.
I can't tell whether this defines the answer.
'santa's disgusting habit poor' is the wordplay.
'santa' becomes 'claus' (Santa Claus).
'disgusting' indicates anagramming the letters (a disgusting or rotten ordering of the letters).
'habit'+'poor'='habitpoor'
'habitpoor' anagrammed gives 'trophobia'.
'claus'+'trophobia'='CLAUSTROPHOBIA'
Can you help me to learn more?
(Other definitions for claustrophobia that I've seen before include "Fear of confined spaces" , "major worry over space" , "Fear of confinement" , "feeling of being badly stuck in a corner?" .)