Elves dancing across top of shoe container (6)
I believe the answer is:
vessel
'container' is the definition.
(vessel is a kind of container)
'elves dancing across top of shoe' is the wordplay.
'dancing' is an anagram indicator.
'across' means one lot of letters goes inside another.
'top of' says to take the initial letters.
The initial letter of 'shoe' is 's'.
'elves' is an anagram of 'vesel'.
'vesel' placed around 's' is 'VESSEL'.
(Other definitions for vessel that I've seen before include "Watercraft or water container" , "bowl?" , "Ship, or receptacle for liquid" , "one swimming in blood?" , "Large boat; container" .)