Try twice to swallow vitamin for painful condition (9)
I believe the answer is:
heartburn
'painful condition' is the definition.
(medical condition)
'try twice to swallow vitamin' is the wordplay.
'try twice' means two replacements for 'try'.
'try' becomes 'hear' (as in to try someone in court or hear their case).
'try' becomes 'turn' ('let me have a try').
'to swallow' is an insertion indicator.
'vitamin' becomes 'B' (B vitamin is an example).
'turn' going around 'b' is 'tburn'.
'hear'+'tburn'='HEARTBURN'
'for' is the link.
(Other definitions for heartburn that I've seen before include "Painful sensation" , "Indigestion of cardiac origin?" , "Chest pain" , "Hot sensation in lower chest from indigestion" , "Acid indigestion" .)