human element; collusion
Step-by-step explanation:
Let us understand the act of collusion.
A secret agreement between two person or two parties to involve themselves in fraud act.
Here the situation is, the clerk has not received raise in salary. So he want to take revenge and has plan to sell the office items for his personal gain. So this is an act of collusion.
Another real life example:
A deal between supplier and retailer to increase the price illegally to have personal benefits.
Let us understand the term human element in a positive way
Human element is the organized way of approach by teams and individual to achieve organizational goals.