Incline to include leader of revolution in fashion (5)
I believe the answer is:
trend
'fashion' is the definition.
(thesaurus)
'incline to include leader of revolution' is the wordplay.
'incline' becomes 'tend' ('tend' can be a synonym of 'incline'**).
'to include' means one lot of letters goes inside another.
'leader of' indicates taking the first letters.
The first letter of 'revolution' is 'r'.
'tend' going around 'r' is 'TREND'.
'in' acts as a link.
(Other definitions for trend that I've seen before include "Med. port, taken by Crusaders" , "Prevailing tendency" , "Bias" , "shift" , "swing" .)