Could this suggest daughter only nine? Imagine! (7)
I believe the answer is:
pretend
'imagine' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for pretend that I've seen before include "Simulate, feign" , "Behave unnaturally" , "Imaginary, make-believe" , "Simulated" , "Imagined" .)