High Court division disposes of hollow ruby, making fortune (6)
I believe the answer is:
chance
'ruby making fortune' is the definition.
'chance' can be an answer for 'fortune' (synonyms). I'm unsure of the 'ruby making' bit.
'high court division disposes of hollow' is the wordplay.
'high court division' becomes 'chan' (I can't explain this - if you can you should give a lot more credence to this answer).
'disposes of' becomes 'castsaside' ('cast aside' can be a synonym of 'dispose of').
'hollow' suggests removing the centre.
'castsaside' with its middle removed is 'ce'.
'chan'+'ce'='CHANCE'
(Other definitions for chance that I've seen before include "Run a risk" , "Happenstance" , "Coincidence" , "Odds" , "Happen - fortuitous" .)