Attractive, easily remembered (6)
I believe the answer is:
catchy
This clue is a double definition.
'attractive' is the first definition.
(similar in meaning)
'easily remembered' is the second definition.
(I've seen this before)
(Other definitions for catchy that I've seen before include "Of tune, lilting and easy to remember" , "(Of a tune) likely to remain in one's head" , "Easy to remember and sing" , "Staying in the mind of a tune" , "Notedly attractive" .)