Golf -- after mother fetched grub (6)
I believe the answer is:
maggot
'grub' is the definition.
(maggot is a kind of grub)
'golf after mother fetched' is the wordplay.
'golf' becomes 'g' (phonetic alphabet: alpha, bravo, charlie etc.).
'after' means one lot of letters go next to another.
'mother' becomes 'ma' (ma is a kind of mother).
'fetched' becomes 'got' ('get' can be a synonym of 'fetch').
'g' put after 'ma' is 'mag'.
'mag'+'got'='MAGGOT'
(Other definitions for maggot that I've seen before include "Larva often found in decaying matter" , "Legless larva" , "Fly larva" , "Larva of housefly or bluebottle" , "Blowfly larva" .)