Make matters worse? One left out cash! (7)
I believe the answer is:
capital
'out cash' is the definition.
'capital' can be an answer for 'cash' (thesaurus). I am not sure about the 'out' bit.
'make matters worse? one left' is the wordplay.
'make matters worse?' becomes 'capita' (I can't explain this - if you can you should believe this answer much more).
'one left' becomes 'L' (common abbreviation).
'capita'+'l'='CAPITAL'
Can you help me to learn more?
(Other definitions for capital that I've seen before include "source of profit" , "It's terrific in the big city" , "Principal city" , "Wellington, say" , "City - finance - very good" .)