Spice Girl and Irishman barely aged (9)
I believe the answer is:
geriatric
'aged' is the definition.
Although both the answer and definition are adjectives, I don't see how one could define the other.
'spice girl and irishman barely' is the wordplay.
'spice girl' becomes 'Geri' (Geri Halliwell).
'and' is a charade indicator (letters next to each other).
'irishman' becomes 'patrick' (Patrick is a common Irish name).
'barely' says to take the centre (the word is bare of its external letters).
The middle of 'patrick' is 'atric'.
'geri'+'atric'='GERIATRIC'
Can you help me to learn more?
(Other definitions for geriatric that I've seen before include "Relating to old people" , "treatment of the elderly" , "past it" , "Oldie" .)