Cheer's echo not appearing after expected interval (5)
I believe the answer is:
elate
'cheer's' is the definition.
(to elate is to cheer or make happy)
'echo not appearing after expected interval' is the wordplay.
'echo' becomes 'e' (phonetic alphabet: alpha, bravo, charlie etc.).
'not appearing after expected interval' becomes 'late' (I can't justify this - if you can you should believe this answer much more).
'e'+'late'='ELATE'
Can you help me to learn more?
(Other definitions for elate that I've seen before include "Lift (the spirits)" , "Fill with optimism" , "Uplift (mood)" , "cheer" , "Exhilarate, put in high spirits" .)