Conspicuous source of information, say, taken in at once, almost (9)
I believe the answer is:
prominent
'conspicuous' is the definition.
(similar in meaning)
'source of information say taken in at once almost' is the wordplay.
'source of information say' becomes 'mine' (someone might be called a mine of information).
'taken in' is an insertion indicator.
'at once' becomes 'pronto' (pronto can mean at once or quickly).
'almost' means to remove the last letter (most of the word but not all of it).
'pronto' with its final letter removed is 'pront'.
'mine' going inside 'pront' is 'PROMINENT'.
(Other definitions for prominent that I've seen before include "sticking up" , "Projecting; famous" , "Important; protuberant" , "Important, famous" , "Conspicuous or outstanding" .)