Genuine because hesitation included (7)
I believe the answer is:
sincere
'genuine' is the definition.
(sincere can mean authentic or genuine)
'because hesitation included' is the wordplay.
'because' becomes 'since' ('since' can mean 'because').
'hesitation' becomes 'er' (sound made while hesitating - um, er).
'included' means one lot of letters goes inside another.
'since' going around 'er' is 'SINCERE'.
(Other definitions for sincere that I've seen before include "Lacking in deceit" , "Earnest" , "Unfeigned, genuine" , "Free from deceit" , "natural?" .)