Rid one's mind of tragic figure stopping sister cycling (7)
I believe the answer is:
unlearn
'rid one's mind of' is the definition.
(to unlearn is to forget or ignore something)
'tragic figure stopping sister cycling' is the wordplay.
I cannot really understand how this works, but
'figure' could be 'lear' (I have seen 'tragic figure' mean 'lear' so perhaps 'figure' could also mean 'lear') and 'lear' is present in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for unlearn that I've seen before include "Deliberately forget" , "Try to forget something" , "Cease to hold (previous teaching)" .)