Breaking rule again? Such a pain (9)
I believe the answer is:
neuralgia
'such a pain' is the definition.
(neuralgia is a kind of pain)
'breaking rule again?' is the wordplay.
'breaking' is an anagram indicator.
'rule'+'again'='ruleagain'
'ruleagain' anagrammed gives 'NEURALGIA'.
(Other definitions for neuralgia that I've seen before include "illness" , "Acute pain of the nerves" , "intermittent pain" , "Pain from damaged nerve" , "Shooting pains" .)