Happen to see end of play, memorable (6)
I believe the answer is:
catchy
'memorable' is the definition.
(something catchy is easy to remember)
'happen to see end of play' is the wordplay.
'happen to see' becomes 'catch'.
'end of' says to take the final letters.
The final letter of 'play' is 'y'.
'catch'+'y'='CATCHY'
(Other definitions for catchy that I've seen before include "(Of a tune) likely to remain in one's head" , "like certain tunes?" , "Readily caught, like a tune" , "Notedly attractive" , "Of a tune, lively and easy to remember" .)