Memorable arrest? Yes (6)
I believe the answer is:
catchy
'memorable' is the definition.
(thesaurus)
'arrest? yes' is the wordplay.
'arrest?' becomes 'catch' ('catch' can be a synonym of 'arrest').
'yes' becomes 'y'.
'catch'+'y'='CATCHY'
(Other definitions for catchy that I've seen before include "Of tune, lilting and easy to remember" , "Attention-grabbing" , "Of a tune, lively and easy to remember" , "Musically memorable" , "what's full of snags, perhaps" .)