Stretch a leg and note changes (8)
I believe the answer is:
elongate
'stretch' is the definition.
('elongate' can be a synonym of 'stretch')
'a leg and note changes' is the wordplay.
'and' means one lot of letters go next to another (I've seen this in other clues).
'changes' indicates an anagram.
'a'+'leg'='aleg'
'aleg' after 'note' is 'notealeg'.
'notealeg' with letters rearranged gives 'ELONGATE'.
(Other definitions for elongate that I've seen before include "Stretch, lengthen" , "Widen" , "Gone late oddly to extend" , "Open out" , "grow further" .)