Modest crater surrounding church (6)
I believe the answer is:
decent
'modest' is the definition.
(I've seen this before)
'crater surrounding church' is the wordplay.
'crater' becomes 'dent' (I can't explain this - if you can you should give a lot more credence to this answer).
'surrounding' is an insertion indicator.
'church' becomes 'CE' (abbreviation for Church of England).
'dent' enclosing 'ce' is 'DECENT'.
Can you help me to learn more?
(Other definitions for decent that I've seen before include "Fairly good" , "Not immodest, generous" , "Nice" , "Obliging or modest" , "Adequately covered" .)