Began hugging learner that's alarmed (8)
I believe the answer is:
startled
'alarmed' is the definition.
(thesaurus)
'began hugging learner' is the wordplay.
'began' becomes 'started' ('start' can be a synonym of 'begin').
'hugging' means one lot of letters goes inside another.
'learner' becomes 'l'.
'started' enclosing 'l' is 'STARTLED'.
'that's' is the link.
(Other definitions for startled that I've seen before include "Caused sudden alarm" , "Affrighted" , "Shocked, alarmed" , "Suddenly alarmed" , "Frightened or surprised suddenly" .)