True crime about to involve church (7)
I believe the answer is:
sincere
'true' is the definition.
(similar in meaning)
'crime about to involve church' is the wordplay.
'crime' becomes 'sin'.
'about' becomes 're' ('re' means regarding or about).
'to involve' indicates putting letters inside (inserted letters get involved).
'church' becomes 'CE' (abbreviation for Church of England).
'sin'+'re'='sinre'
'sinre' going around 'ce' is 'SINCERE'.
(Other definitions for sincere that I've seen before include "like informal correspondents?" , "Perfect" , "Genuine and honest" , "Genuine; deceit-free" , "Unaffected" .)