Friend carrying one's bucket (4)
I believe the answer is:
pail
'bucket' is the definition.
('pail' can be a synonym of 'bucket')
'friend carrying one's' is the wordplay.
'friend' becomes 'pal' (pal is a kind of friend**).
'carrying' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'pal' enclosing 'i' is 'PAIL'.
(Other definitions for pail that I've seen before include "A bucket as for water" , "Container; sounds like dim" , "Water carrier" , "Vessel for carrying liquids" , "A bucket - the kind Jack and Jill used" .)