Cash disheartened Firth or Farrell (4)
I believe the answer is:
coin
'cash' is the definition.
(thesaurus)
'disheartened firth or farrell' is the wordplay.
'disheartened' says to hollow out the word (remove centre letters) (the middle or heart is removed).
'firth or farrell' becomes 'colin' (I've seen this in another clue).
'colin' with its middle taken out is 'COIN'.
(Other definitions for coin that I've seen before include "Create (phrase); metal token" , "Invent (a new phrase)" , "Mint" , "Metal currency" , "American quarter, for example" .)