Bill seen in Whitstable (3)
I believe the answer is:
tab
'bill' is the definition.
(a tab is a bill at a bar)
'in whitstable' is the wordplay.
'in' indicates the answer is hidden within the clue.
'TAB' is hidden within 'whitstable'.
'seen' acts as a link.
(Other definitions for tab that I've seen before include "Ring pull" , "Bar tally; small flap" , "Tally of orders in bar" , "Running bar bill" , "Text indent key" .)