After six look around entrance to institute - requirement for guard (9)
I believe the answer is:
vigilance
'for guard' is the definition.
(thesaurus)
'after six look around entrance to institute' is the wordplay.
'after' says to put letters next to each other.
'six' becomes 'vi' ('vi' can be a synonym of 'six').
'look' becomes 'glance' (glance is a kind of look**).
'around' means one lot of letters goes inside another.
'entrance to' indicates taking the first letters.
The first letter of 'institute' is 'i'.
'glance' going around 'i' is 'gilance'.
'vi' put next to 'gilance' is 'VIGILANCE'.
'requirement' is the link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for vigilance that I've seen before include "Alertness, watchfulness" , "Keeping careful watch on" .)