Memorable (13)
There are a few possibilities for this:
unforgettable
(Other definitions for unforgettable that I've seen before include "stuck in my brain?" , "Nat King Cole's memorable song?" , "Striking" , "Noteworthy" , "Highly memorable" .)
'memorable' is the definition.
(something catchy is easy to remember)
This is the entire clue.
(Other definitions for catchy that I've seen before include "Tuneful and easily remembered" , "Musically memorable" , "Type of tune that stays in the memory" , "(Of tune) infectious" , "Hummable" .)