Struck (7)
'struck' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for smitten that I've seen before include "Very much in love" , "Head over heels in love" , "Affected or struck by, disease or desire" , "Struck (by love?)" , "Obsessed (when in love?)" .)
(Other definitions for cracked that I've seen before include "Slangily eccentric - or broken" , "Having fissures" , "Fractured" .)