Container very small with bottom knocked out (3)
I believe the answer is:
tin
'container' is the definition.
(I know that tin is a type of container)
'very small with bottom knocked out' is the wordplay.
'very small' becomes 'tiny' (I've seen this in another clue).
'with bottom knocked out' means to remove the last letter (the letter at the bottom of the word is removed).
'tiny' with its final letter taken off is 'TIN'.
(Other definitions for tin that I've seen before include "Silvery metallic element" , "A silvery-white metal often in cans" , "1 down, symbol Sn" , "Money" , "Cornish metal?" .)