Dental problem, a sore point, say, long after (9)
I believe the answer is:
toothache
'dental problem' is the definition.
(I've seen this before)
'a sore point say long after' is the wordplay.
'a sore point say' becomes 'tooth' (I can't justify this - if you can you should give a lot more credence to this answer).
'long' becomes 'ache' (to long for something is to ache for it).
'after' says to put letters next to each other.
'tooth'+'ache'='TOOTHACHE'
Can you help me to learn more?
(Other definitions for toothache that I've seen before include "Oral discomfort" , "It causes grief" , "Odontalgia" , "Dental problem" , "Trouble with choppers" .)