Melissa can be unmotivated (7)
I believe the answer is:
aimless
'unmotivated' is the definition.
(I've seen this before)
'melissa can be' is the wordplay.
'can be' indicates anagramming the letters.
'melissa' anagrammed gives 'AIMLESS'.
(Other definitions for aimless that I've seen before include "at a loose end" , "Lacking purpose" , "Without purpose, like Melissa" , "Without objectives" , "Without direction or ambition" .)