With abandon, a motherless man can cause a rising (6)
I believe the answer is:
leaven
'cause a rising' is the definition.
(as in leavening dough)
'with abandon a motherless man' is the wordplay.
'with' means one lot of letters go next to another.
'abandon' becomes 'leave' (to abandon something is to leave it behind).
'a motherless man' becomes 'n' (knight, a man in chess. I am not sure about the 'motherless' bit.).
'leave'+'n' is 'LEAVEN'.
'can' acts as a link.
Can you help me to learn more?
(Other definitions for leaven that I've seen before include "Add yeast to" , "Substance that produces fermentation in dough" , "Yeast or other raising agent" , "Cause dough to rise" , "Substance that makes dough ferment" .)