Hear end of symphony that's memorable (6)
I believe the answer is:
catchy
'memorable' is the definition.
(something catchy is easy to remember)
'hear end of symphony' is the wordplay.
'hear' becomes 'catch' (catching is a kind of hearing).
'end of' says to take the final letters.
The final letter of 'symphony' is 'y'.
'catch'+'y'='CATCHY'
'that's' is the link.
(Other definitions for catchy that I've seen before include "Readily caught, like a tune" , "what's full of snags, perhaps" , "Notedly attractive" , "Of a tune, lively and easy to remember" , "Attention-grabbing" .)