Current facility supporting large debt (9)
I believe the answer is:
liability
'debt' is the definition.
(synonyms)
'current facility supporting large' is the wordplay.
'current' becomes 'I' (physics symbol).
'facility' becomes 'ability' (I can't explain this - if you can you should give a lot more credence to this answer).
'supporting' means one lot of letters go next to another (in a down clue, some letters go below others).
'large' becomes 'L' (eg in clothes sizes).
'i'+'ability'='iability'
'iability' after 'l' is 'LIABILITY'.
Can you help me to learn more?
(Other definitions for liability that I've seen before include "Hindrance" , "duty" , "Debt; drawback" , "Financial obligation" , "Millstone" .)