He's out of work, but don't despair! (4)
I believe the answer is:
hope
'he's out of work but don't despair' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'he's out of work but' is the wordplay.
'out' means to remove the last letter.
'of' becomes 'o''.
'work but' becomes 'pe' (I am not sure about this - if you are sure you should believe this answer much more).
'he' with its final letter removed is 'h'.
'h'+'o'+'pe'='HOPE'
Can you help me to learn more?
(Other definitions for hope that I've seen before include "Longing" , "English novelist" , "Confident expectation" , "Aspiration" , "Companion to faith and charity" .)