Backtracking oil producer's at first an advocate of Home Rule (10)
I believe the answer is:
separatist
'an advocate of home rule' is the definition.
(person advocating home rule for a colonised nation)
'backtracking oil producer's at first' is the wordplay.
'backtracking' is a reversal indicator.
'oil producer's' becomes 'rapes' (as in rape seed oil).
'first' becomes 'ist'.
'rapes' reversed gives 'separ'.
'separ'+'at'+'ist'='SEPARATIST'
(Other definitions for separatist that I've seen before include "Wanting independence" , "Rebel" , "dissenter" , "One who would break up a union" , "One wishing to break away" .)