Doctor recants notion causing alarm (13)
I believe the answer is:
consternation
'alarm' is the definition.
(synonyms)
'doctor recants notion' is the wordplay.
'doctor' indicates an anagram.
'recants'+'notion'='recantsnotion'
'recantsnotion' is an anagram of 'CONSTERNATION'.
'causing' acts as a link.
(Other definitions for consternation that I've seen before include "Feelings of dismay" , "Alarm" , "Dismay - cast-iron tenon (anag)" , "Anxiety, dismay" , "Worry" .)