Survey, as per usual, misses one essential truth (7)
I believe the answer is:
perusal
'survey' is the definition.
(thesaurus)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for perusal that I've seen before include "Study or scrutiny" , "Reading, examination" , "Scanning, reading" , "Careful look" , "Thorough reading" .)