Almost having hot drink knocked back (4)
I believe the answer is:
nigh
'almost' is the definition.
(nigh can mean almost or nearly)
'hot drink knocked back' is the wordplay.
'hot' becomes 'h' (abbreviation eg on taps).
'drink' becomes 'gin' (gin is an alcoholic drink).
'knocked back' shows that the letters should be reversed in order.
'h'+'gin'='hgin'
'hgin' backwards is 'NIGH'.
'having' is the link.
(Other definitions for nigh that I've seen before include "Near, as in archaic usage" , "All but one" , "Near (old use)" , "Just round the corner" , "Nearby" .)