That man's visiting a seedy joint -- tacky! (8)
I believe the answer is:
adhesive
'tacky' is the definition.
(I've seen this before)
'that man's visiting a seedy joint' is the wordplay.
'that man's' becomes 'he's' (he's).
'visiting' is an insertion indicator.
'seedy joint' becomes 'dive' (I've seen this in another clue).
'a'+'dive'='adive'
'hes' going inside 'adive' is 'ADHESIVE'.
(Other definitions for adhesive that I've seen before include "doing some bonding" , "Substance that sticks" , "Tending to stick" , "very clingy" , "What a sticker" .)