Melissa goes astray, lacking direction (7)
I believe the answer is:
aimless
'lacking direction' is the definition.
(I've seen this before)
'melissa goes astray' is the wordplay.
'goes astray' indicates an anagram.
'melissa' anagrammed gives 'AIMLESS'.
(Other definitions for aimless that I've seen before include "lacking direction" , "With no plan or programme" , "without sense of purpose" , "Without direction or ambition" , "Drifting - Melissa (anag)" .)