Get your money on "Half-back" early (7)
I believe the answer is:
betimes
'early' is the definition.
(synonyms)
'get your' is the wordplay.
'get' becomes 'be' ('get' can mean 'come to be').
'your' becomes 'times' (I can't justify this - if you can you should believe this answer much more).
'be'+'times'='BETIMES'
'money on half-back' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for betimes that I've seen before include "Soon or early (Old English)" , "speedily" .)