Keeper, Chelsea's No. 1, raised game before a right back seizes ball (7)
I believe the answer is:
curator
'keeper' is the definition.
(I know that keeper can be written as curator)
'before a right back seizes ball' is the wordplay.
'before' says to put letters next to each other.
'a right' becomes 'r' (common abbreviation).
'back' becomes 'curat' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'seizes' is an insertion indicator.
'ball' becomes 'o' (O looks like a ball).
'r' after 'curat' is 'curatr'.
'curatr' enclosing 'o' is 'CURATOR'.
'chelsea's no 1 raised game' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for curator that I've seen before include "Keeper of a collection" , "Person in charge of a museum" , "Custodian of a collection" , "Museum keeper" , "Museum officer" .)