A rotter for example coming back to sponge (5)
I believe the answer is:
cadge
'to sponge' is the definition.
(synonyms)
'a rotter for example coming back' is the wordplay.
'a rotter' becomes 'cad' (I've seen this in another clue).
'for example' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin).
'coming back' says the letters should be written in reverse.
'eg' reversed gives 'ge'.
'cad'+'ge'='CADGE'
(Other definitions for cadge that I've seen before include "Scrounge (money, etc)" , "Get by begging" , "Sponge (money, etc)" , "Bum" , "Scrounge, sponge" .)