Friend sure to throw in a scan (7)
I believe the answer is:
perusal
'a scan' is the definition.
(I have seen 'thorough scan' mean 'perusal' so perhaps 'scan' could also mean 'perusal')
'friend sure to throw in' is the wordplay.
'friend' becomes 'pal' (pal is a kind of friend**).
'to throw' indicates an anagram.
'in' is an insertion indicator.
'sure' anagrammed gives 'erus'.
'pal' placed around 'erus' is 'PERUSAL'.
(Other definitions for perusal that I've seen before include "worth a close look" , "thorough scan" , "Thorough read-through" , "Careful look" , "Scanning, reading" .)