Pole bowled over with vigour, dismissing first one (8)
I believe the answer is:
bowsprit
'pole' is the definition.
(bowsprit is a kind of pole)
'bowled over with vigour dismissing first one' is the wordplay.
'bowled over with' becomes 'bow' (this might be a standard abbreviation I've not previously seen).
'vigour' becomes 'esprit'.
'dismissing first one' means to remove the first letter.
'esprit' with its first letter taken off is 'sprit'.
'bow'+'sprit'='BOWSPRIT'
Can you help me to learn more?
(Other definitions for bowsprit that I've seen before include "Spar projecting from front of a boat" , "Spar projecting from the front of a sailing vessel" , "See component of boat" , "Projecting spar at front of sailing ship" .)