Move slowly in church (4)
I believe the answer is:
inch
'move slowly' is the definition.
(I've seen this before)
'in church' is the wordplay.
'church' becomes 'ch' (common abbreviation).
'in'+'ch'='INCH'
(Other definitions for inch that I've seen before include "See 12" , "Small Scottish island" , "Move in tiny increments" , "Edge slowly" , "One of a 2 down in a foot" .)