Old leaves beginning to separate from husks and straw (6)
I believe the answer is:
thresh
'separate from husks and straw' is the definition.
I can't judge whether this definition defines the answer.
'old leaves beginning' is the wordplay.
'leaves' indicates named letters should be taken away.
'beginning' becomes 'threshold' (e.g. threshold of a dazzling career).
'threshold' with 'old' taken out is 'THRESH'.
'to' is the link.
Can you help me to learn more?
(Other definitions for thresh that I've seen before include "Separate grain from (eg, corn)" , "Scots rush" , "Separate grain from (corn); move violently" , "Separate grain with flail" , "Separate seed from grain" .)