Preacher on box in the Levant, not hard — member looking up is captivated! (13)
I believe the answer is:
televangelist
'preacher on box' is the definition.
(preacher on television or 'the box')
'the levant not hard member looking up is captivated' is the wordplay.
I cannot really see how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is present in the answer.
'up' could be 'is' (I've seen this in other clues) and 'is' is found in the answer.
This explanation may well be incorrect...
'in' acts as a link.
(Other definitions for televangelist that I've seen before include "Revivalist who broadcasts" , "TV preacher" .)