Rhode Island church is full (4)
I believe the answer is:
rich
'is full' is the definition.
(thesaurus)
'rhode island church' is the wordplay.
'rhode island' becomes 'ri' (US postal abbreviation).
'church' becomes 'ch' (common abbreviation**).
'ri'+'ch'='RICH'
(Other definitions for rich that I've seen before include "Abundant" , "Loaded" , "very funny?" , "Affluent" , "Splendid" .)