Wrong George! Boy on front gate gets rising and falling intonation (8)
I believe the answer is:
singsong
'intonation' is the definition.
(singsong is a kind of intonation)
'wrong george boy on front gate' is the wordplay.
'wrong' becomes 'sin' (I've seen this before).
'george' becomes 'g'.
'boy on front gate' becomes 'song' (I am not sure about this - if you are sure you should believe this answer much more).
'sin'+'g'+'song'='SINGSONG'
'gets rising and falling' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for singsong that I've seen before include "musical get-together" , "Vocal gathering" , "monotonous rhythm" , "choral performance" , "Informal choral session" .)