Five past four (4)
I believe the answer is:
nine
This clue could be a double definition.
'five' is the first definition.
(thesaurus)
'past four' is the second definition.
The answer and definition can be both quantities as well as being singular nouns.
Perhaps there's a link between them I don't understand?
Can you help me to learn more?
(Other definitions for nine that I've seen before include "Square number" , "dancing ladies?" , "Square next up after four" , "Number of Muses and days in a Novena" , "Days Lady Jane 5 ac reigned" .)