Buying church benefits my son, I suspect (6)
I believe the answer is:
simony
'buying church benefits' is the definition.
(simony is buying or selling church benefits)
'my son i suspect' is the wordplay.
'suspect' is an anagram indicator (a suspicious or unusual spelling).
'my'+'son'+'i'='mysoni'
'mysoni' is an anagram of 'SIMONY'.
(Other definitions for simony that I've seen before include "Dealing in church property" , "purchase of church office" , "cloth trade" , "The buying or selling of ecclesiastical privileges" , "Buying and selling of ecclesiastical offices" .)