Very large source of light for 1D (3)
I believe the answer is:
sol
'light for 1d' is the definition.
I can't tell whether this defines the answer.
'very large source' is the wordplay.
'very' becomes 'so' (both can mean 'extremely').
'source' indicates taking the first letters (source can mean a beginning or origin).
The first letter of 'large' is 'l'.
'so'+'l'='SOL'
'of' is the link.
Can you help me to learn more?
(Other definitions for sol that I've seen before include "Note, old french coin" , "The Sun (or Campbell?)" , "Note; Peruvian currency" , "Personification of the sun" , "The sun in 12 Across" .)