Singer's money runs out (4)
I believe the answer is:
bass
'singer's' is the definition.
(bass is a kind of singer)
I cannot understand how the rest of the clue works.
(Other definitions for bass that I've seen before include "Fish for the low-voiced" , "Fish; male singing voice" , "Fish; deep voice" , "Scottish rock" , "Fish (which sings?)" .)