Record-holder needs rest shortly before historic victory (6)
I believe the answer is:
sleeve
'record-holder' is the definition.
(I've seen this before)
'rest shortly before historic victory' is the wordplay.
'rest' becomes 'sleep' (sleeping is a kind of resting).
'shortly' means to remove the last letter.
'before historic victory' becomes 've' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'sleep' with its last letter taken off is 'slee'.
'slee'+'ve'='SLEEVE'
'needs' acts as a link.
Can you help me to learn more?
(Other definitions for sleeve that I've seen before include "Part of a shirt or jacket" , "An arm goes into it - or a music album" , "It's attached to the armhole" , "Some wear their heart on it" , "Record-holder" .)