Grab tin at church (6)
I believe the answer is:
snatch
'grab' is the definition.
('snatch' can be a synonym of 'grab')
'tin at church' is the wordplay.
'tin' becomes 'sn' ('Sn' can be a synonym of 'tin').
'church' becomes 'ch' (common abbreviation).
'sn'+'at'+'ch'='SNATCH'
(Other definitions for snatch that I've seen before include "Deftly seize" , "Seize; musical fragment" , "Weightlifting lift" , "Bit of a song" , "Piece of music" .)