Rotter, for example, coming back to beg (5)
I believe the answer is:
cadge
'to beg' is the definition.
(I know that beg is a is a more specific form of the action of cadge)
'rotter for example coming back' is the wordplay.
'rotter' becomes 'cad' (a cad is a dishonourable person).
'for example' becomes 'e.g.' (short for 'exempli gratia', 'for example' in Latin).
'coming back' says the letters should be written backwards.
'eg' in reverse letter order is 'ge'.
'cad'+'ge'='CADGE'
(Other definitions for cadge that I've seen before include "Sponge (eg money)" , "Get money by sponging" , "Try to borrow" , "Scrouge, ask for" , "Scrounge (money, etc)" .)