Counterfoil in small container (4)
I believe the answer is:
stub
'counterfoil' is the definition.
('stub' can be a synonym of 'counterfoil')
'small container' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'container' becomes 'tub' (tub is a kind of container**).
's'+'tub'='STUB'
'in' is the link.
(Other definitions for stub that I've seen before include "Counterfoil, of a cheque say" , "Residue of cigarette or cheque" , "Bust (anag.)" , "30 [FAG END]" , "Wee bit of pencil, eg," .)