Ruler therefore in poor area is the cause of rising (6,4)
I believe the answer is:
baking soda
'the cause of rising' is the definition.
I can't tell whether this defines the answer.
'ruler therefore in poor area' is the wordplay.
'ruler' becomes 'king' (king is a kind of ruler).
'therefore' becomes 'so' (I've seen this in another clue).
'in' is an insertion indicator.
'poor area' becomes 'bada' (I can't justify this - if you can you should believe this answer much more).
'king'+'so'='kingso'
'kingso' put into 'bada' is 'BAKING-SODA'.
'is' is the link.
Can you help me to learn more?
(Other definitions for baking soda that I've seen before include "Common name for sodium bicarbonate" , "possible antacid" .)