Different leader of course sent to the gallows (7)
I believe the answer is:
changed
'different' is the definition.
(I've seen this before)
'leader of course sent to the gallows' is the wordplay.
'leader of' indicates taking the first letters.
'sent to the gallows' becomes 'hanged' (I've seen this in another clue).
The initial letter of 'course' is 'c'.
'c'+'hanged'='CHANGED'
(Other definitions for changed that I've seen before include "Modified" , "Turned" , "Altered - substituted" , "Different" .)