Twist, say, for rising dynasty (6)
I believe the answer is:
orphan
'twist say' is the definition.
(I know that Oliver Twist is a orphan)
'for rising dynasty' is the wordplay.
'for' becomes 'pro' (as in being 'pro' something).
'rising' is a reversal indicator (going up in a down clue).
'dynasty' becomes 'han' (I've seen this before).
'pro' back-to-front is 'orp'.
'orp'+'han'='ORPHAN'
(Other definitions for orphan that I've seen before include "One without mother or father" , "Child without parent" , "Child left" , "Child without parents" , "Oliver?" .)