Bag half of goals at Chelsea (7)
I believe the answer is:
satchel
'bag' is the definition.
(satchel is a type of bag)
'half of goals at chelsea' is the wordplay.
'half of' indicates a hidden word (half of the letters in the selection).
'SATCHEL' is hidden within 'goals at chelsea'.
(Other definitions for satchel that I've seen before include "Bag with a flap and strap" , "Shoulder bag as for schoolbooks" , "Schoolchild's carrier" , "Schoolbag for children's books" , "Bag for school books" .)