Varnish — the fellow has two litres in container (7)
I believe the answer is:
shellac
'varnish' is the definition.
(I know that shellac is a more specific form of the action the varnish)
'fellow has two litres in container' is the wordplay.
'fellow' becomes 'he' ('he' refers to a man).
'has' means one lot of letters go next to another.
'two litres' becomes 'LL' (the abbreviation for 'litre' repeated).
'in' is an insertion indicator.
'container' becomes 'sac' ().
'he'+'ll'='hell'
'hell' put inside 'sac' is 'SHELLAC'.
'the' acts as a link.
(Other definitions for shellac that I've seen before include "Varnish derived from insect secretion" , "Thin varnish used to finish wood" , "Resin from trees" , "(it's in old records)" , "Take a shine to" .)