Former teacher produces great painting (3,6)
I believe the answer is:
old master
'great painting' is the definition.
'old master' can be an answer for 'painting' (old master can mean a painting by an old master). I am not sure about the 'great' bit.
'former teacher' is the wordplay.
'former' becomes 'old' (both can mean previous).
'teacher' becomes 'master' (I've seen this before).
'old'+'master'='OLD MASTER'
'produces' acts as a link.
Can you help me to learn more?
(Other definitions for old master that I've seen before include "Classic painting" , "Classic painter" , "Do armlets serve for great painter of yore?" , "Famous painting" , "Mr Chips, say?" .)