Nothing in pub for a snuffling customer? (4)
I believe the answer is:
boar
'a snuffling customer?' is the definition.
(boars are animals which snuffle)
'nothing in pub' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'in' means one lot of letters goes inside another.
'pub' becomes 'bar' (I've seen this before).
'o' inserted within 'bar' is 'BOAR'.
'for' acts as a link.
(Other definitions for boar that I've seen before include "Wild pig sounds tedious" , "Wild swine" , "Sow's mate" , "Wild animal, sounds like drill" , "Male swine" .)