No point going back for old English preacher (6)
I believe the answer is:
bunyan
'old english preacher' is the definition.
(writer and preacher John Bunyan)
'no point going back' is the wordplay.
'no' becomes 'nay' (I've seen this before).
'point' becomes 'nub' (I've seen this before).
'going back' shows that the letters should be reversed in order.
'nay'+'nub'='naynub'
'naynub' reversed gives 'BUNYAN'.
'for' acts as a link.
(Other definitions for bunyan that I've seen before include "John . . . . . . wrote 'The Pilgrim's Progress'" , "The Pilgrim's Progress author, d. 1688" , "author John" , "Writer" , "John ... wrote 'The Pilgrim's Progres'" .)