The man's in a joint that's sticky (8)
I believe the answer is:
adhesive
'sticky' is the definition.
('adhesive' can be similar in meaning to 'sticky')
'the man's in a joint' is the wordplay.
'the man's' becomes 'hes' (he's).
'in' is an insertion indicator.
'joint' becomes 'dive' (I've seen this before).
'a'+'dive'='adive'
'hes' inserted into 'adive' is 'ADHESIVE'.
'that's' is the link.
(Other definitions for adhesive that I've seen before include "Tending to stick" , "What a sticker" , "Tacky" , "doing some bonding" , "It sticks things together" .)