Steal tin at church (6)
I believe the answer is:
snatch
'steal' is the definition.
(thesaurus)
'tin at church' is the wordplay.
'tin' becomes 'Sn' (Sn is the chemical symbol for tin).
'church' becomes 'ch' (common abbreviation).
'sn'+'at'+'ch'='SNATCH'
(Other definitions for snatch that I've seen before include "Seize quickly, grab" , "heist" , "Seize abruptly" , "Grab rudely, hastily" , "weightlifting move" .)