Corresponding addition following consideration (12)
I believe the answer is:
afterthought
'corresponding addition' is the definition.
'afterthought' can be an answer for 'addition' (afterthought is a kind of addition). I am not certain of the 'corresponding' bit.
'following consideration' is the wordplay.
'following' becomes 'after' (I've seen this in other clues).
'consideration' becomes 'thought' (I've seen this before).
'after'+'thought'='AFTERTHOUGHT'
Can you help me to learn more?
(Other definitions for afterthought that I've seen before include "Later addition" , "Re-evaluation" , "not an original idea" , "footnote" , "PS for instance" .)