For fish, make the bill out for cash! (5)
I believe the answer is:
bleak
'for fish' is the definition.
(I've seen this before)
'the bill out for cash' is the wordplay.
'the bill' becomes 'beak' ('beak' can be a synonym of 'bill').
'out' indicates putting letters inside.
'for cash' becomes 'l' (I am not sure about this - if you are sure you should believe this answer much more).
'beak' enclosing 'l' is 'BLEAK'.
'make' acts as a link.
Can you help me to learn more?
(Other definitions for bleak that I've seen before include "Stark" , "Gloomy" , "''... House'' (Dickens)" , "Offering little hope" , "Cold and desolate" .)