Good people are not commonly found in Situations Vacant (6)
I believe the answer is:
saints
'good people' is the definition.
'saints' can be an answer for 'people' (saint is a kind of person). I am not certain of the 'good' bit.
'not commonly found in situations vacant' is the wordplay.
'not commonly' becomes 'aint' (non-standard version of 'isn't' or 'aren't').
'found in' indicates putting letters inside.
'vacant' means to remove the middle letters (a vacant or emptied out form of the word).
'situations' with its middle taken out is 'ss'.
'aint' going into 'ss' is 'SAINTS'.
'are' is the link.
Can you help me to learn more?
(Other definitions for saints that I've seen before include "Holy ones" , "Pancras and Alban, for example" , "Southampton FC" , "Canonised men or women" , "Such paragons of virtue" .)