Ageing teachers make great artists (3,7)
I believe the answer is:
old masters
'great artists' is the definition.
'old masters' can be an answer for 'artists' (old master is a kind of artist). I'm unsure of the 'great' bit.
'ageing teachers' is the wordplay.
'ageing' becomes 'old' (similar in meaning).
'teachers' becomes 'masters' (old word for teachers).
'old'+'masters'='OLD MASTERS'
'make' acts as a link.
Can you help me to learn more?
(Other definitions for old masters that I've seen before include "Great Renaissance paintings" , "Classic artists" , "experienced in school?" , "Art's models (anag) - classic painters" , "Great works" .)