Forward but on first shot draw back (7)
I believe the answer is:
onwards
'forward' is the definition.
(I know that forward can be written as onwards)
'on first shot draw back' is the wordplay.
'first shot' becomes 's' (1st letter of 'shot').
'back' shows that the letters should be reversed in order.
's'+'draw'='sdraw'
'sdraw' written backwards gives 'wards'.
'on'+'wards'='ONWARDS'
'but' is the link.
(Other definitions for onwards that I've seen before include "To a point ahead" , "Forwards" , "Moving forward (and upwards?)" , "Going ahead" , "moving in a positive direction" .)