Store offering adult service (5)
I believe the answer is:
amass
'store' is the definition.
(amassing is a kind of storing)
'adult service' is the wordplay.
'adult' becomes 'a' (abbreviation).
'service' becomes 'mass' (kind of church service).
'a'+'mass'='AMASS'
'offering' acts as a link.
(Other definitions for amass that I've seen before include "run up?" , "Gather together, pile up" , "Accumulate, heap up" , "Assemble" , "Sodium chloride" .)