Athens ruinously allows in obtrusively religious actor (8)

I believe the answer is:
thespian
'actor' is the definition.
(synonyms)
'athens ruinously allows in obtrusively religious' is the wordplay.
I cannot really see how this works, but
'religious' could be 'pi' (british abbreviation for pious) and 'pi' is present in the answer.
an anagram of 'athens' is 'thesan' which is present in the left over letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for thespian that I've seen before include "cast member" , "Relating to the theatre" , "Theatrical performer" , "Tragic actor" , "Actor - neat hips (anag)" .)
