Feel empty, needing compassion over dump (3-3)
I believe the answer is:
fly-tip
'dump' is the definition.
(to fly-tip something is to dump it on public land)
'feel empty needing compassion over' is the wordplay.
'empty' means to remove the middle letters.
'needing' means one lot of letters go next to another.
'compassion' becomes 'pity' (synonyms).
'over' says the letters should be written backwards.
'feel' with its centre removed is 'fl'.
'pity' written backwards gives 'ytip'.
'fl'+'ytip'='FLY-TIP'
(Other definitions for fly-tip that I've seen before include "Illegally dump waste" , "Dump rubbish illegally" .)