Actually too young to be a fat lady (5)
I believe the answer is:
eight
This clue could be a double definition.
'actually too young' is the first definition.
Both the definition and answer are adjectives. Maybe you can see an association between them that I can't see?
'a fat lady' is the second definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'to be' is the link.
Can you help me to learn more?
(Other definitions for eight that I've seen before include "Number for a racing boat" , "Cardinal number" , "Rowing boat crew" , "A number, sounds like swallowed" , "Number; rowing boat" .)