Block A, location of Paul's dramatic transformation (9)
I believe the answer is:
damascene
'of paul's dramatic transformation' is the definition.
(as in St Paul's Damascene conversion)
'block a location' is the wordplay.
'block' becomes 'dam' (damming is a kind of blocking).
'location' becomes 'scene' (scene is a kind of location).
'dam'+'a'+'scene'='DAMASCENE'
(Other definitions for damascene that I've seen before include "gold inlay" , "as conversion is described" , "Middle Easterner" , "in Arab city" , "ornament" .)