Irish judge accepts help lifting light up (9)
I believe the answer is:
irradiate
'light up' is the definition.
(irradiate can mean to fill with light)
'irish judge accepts help' is the wordplay.
'irish' becomes 'Ir' (abbreviation).
'judge' becomes 'rate' (rating is a kind of judging).
'accepts' is an insertion indicator.
'help' becomes 'dia' (I can't justify this - if you can you should believe this answer much more).
'rate' placed around 'dia' is 'radiate'.
'ir'+'radiate'='IRRADIATE'
'lifting' acts as a link.
This may not be right. It may be part of another bit of the clue.
(Other definitions for irradiate that I've seen before include "Make bright" , "Shine light on" , "Shed light on" , ""One fine day" would do" .)