Former partner criticises setter regarding development (9)
I believe the answer is:
expansion
'development' is the definition.
(thesaurus)
'former partner criticises setter regarding' is the wordplay.
'former partner' becomes 'ex'.
'criticises' becomes 'pans' (I've seen this before).
'setter regarding' becomes 'ion' (I can't explain this - if you can you should give a lot more credence to this answer).
'ex'+'pans'+'ion'='EXPANSION'
Can you help me to learn more?
(Other definitions for expansion that I've seen before include "Increase in volume" , "fatter" , "Process of increasing in size, volume etc" , "increase in capacity" , "Enlargement" .)