Grub's ending in waste receptacle (3)
I believe the answer is:
bin
'waste receptacle' is the definition.
(I've seen this before)
'grub's ending in' is the wordplay.
'ending' says to take the final letters.
The final letter of 'grub' is 'b'.
'b'+'in'='BIN'
(Other definitions for bin that I've seen before include "Discard" , "Storage receptacle" , "Household rubbish is placed in it" , "Wine store; throw away" , "Waste container" .)