Forward's goal topped by striker's header (4)
I believe the answer is:
Here is my best explanation:
'forward's' is the definition.
'goal topped by striker's header' is the subsidiary indication.
'goal' becomes 'end' ('end' can be a synonym of 'goal').
'topped by' means one lot of letters go next to another.
'striker's header' becomes 's' (I can't explain this - if you can you should give a lot more credence to this answer).
'end' after 's' is 'send'.
(Other definitions for send that I've seen before include "Post", "Despatch, remit", "Cause to go for", "Sentence to a prison term", "broadcast", "Transmit; post", "Mail", "Dispatch by post", "Remit" and "Consign".)