Poor love nobody has fed meal (2,4,6)
I believe the answer is:
on ones uppers
'poor' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'love nobody has fed meal' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'nobody has' becomes 'nones' (I can't explain this - if you can you should give a lot more credence to this answer).
'fed' indicates putting letters inside (one word is 'fed' to another).
'meal' becomes 'supper' (supper is a kind of meal).
'nones' enclosing 'supper' is 'nonesuppers'.
'o'+'nonesuppers'='ON ONES UPPERS'
Can you help me to learn more?
(Other definitions for on ones uppers that I've seen before include "Where to rub 9 [CHERRY BLOSSOM]" , "Very short of money" , "when skint?" , "Impecunious" .)