You will be heard at Christmas (4)
I believe the answer is:
yule
'christmas' is the definition.
(Yule is the Christmas period)
'you will be heard' is the wordplay.
'you' becomes 'yu' (I am not sure about this - if you are sure you should believe this answer much more).
'will' becomes 'll' (contracted form, as in 'he'll' - 'he will').
'be heard' shows a homophone (sound like).
'll' is a homophone of 'le'.
'yu'+'le'='YULE'
'at' is the link.
Can you help me to learn more?
(Other definitions for yule that I've seen before include "Noel" , "Seasonal feast (arch.)" , "Christmas season" , "The feast of Christmas" , "This time of year of old" .)