He'll get what's left, in a manner of speaking? (4)
I believe the answer is:
heir
'he'll' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'get what's left in a manner of speaking?' is the wordplay.
'get' means one lot of letters go next to another.
'what' becomes 'eh' (I've seen this in other clues).
'left' says the letters should be written backwards.
'in a manner of speaking?' becomes 'ir' (I can't explain this - if you can you should give a lot more credence to this answer).
'eh' back-to-front is 'he'.
'he'+'ir' is 'HEIR'.
Can you help me to learn more?
(Other definitions for heir that I've seen before include "Expected successor" , "Successor, next in line" , "Person who succeeds" , "One expected to succeed?" , "One destined to succeed" .)