Hit with vigour, at first, producing a shiner (6,4)
I believe the answer is:
spirit lamp
'a shiner' is the definition.
(something which shines a light)
'hit with vigour at first producing' is the wordplay.
'hit' becomes 'lam' (to 'lam' means to hit hard).
'with' means one lot of letters go next to another.
'vigour' becomes 'spirit'.
'at' means one lot of letters go next to another.
'first producing' becomes 'p' (1st letter of 'producing').
'lam' after 'spirit' is 'spiritlam'.
'spiritlam'+'p'='SPIRIT-LAMP'
(Other definitions for spirit lamp that I've seen before include "this'll lighten things up" , "Meths-burning light" .)