Word with happy or rush (4)
I believe the answer is:
hour
'word with happy or rush' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for hour that I've seen before include "Sixty minutes" , "3,600 seconds" , "Three thousand and six hundred seconds" , "A 24th of a day" , "60 minutes" .)