Working with those people rankled occasionally - self-serving (2,3,4)
I believe the answer is:
on the make
'self-serving' is the definition.
(someone on the make is looking for personal gain)
'working with those people rankled occasionally' is the wordplay.
'working' becomes 'on' (on can mean working or activated).
'with' is a charade indicator (letters next to each other).
'those people' becomes 'them' ('they' refers to a group of people).
'occasionally' indicates alternate letters.
The alternate letters of 'rankled' are 'ake'.
'on'+'them'+'ake'='ON THE MAKE'
(Other definitions for on the make that I've seen before include "intent on profit" , "Ken at home, being intent on gain" , "Intent on gain (colloq.)" , "Trying to get rich quick" , "Hoping for profit" .)