Some remember that collar (6)
I believe the answer is:
bertha
'collar' is the definition.
(I've seen this before)
'some remember that' is the wordplay.
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'BERTHA' is hidden within 'remember that'.
(Other definitions for bertha that I've seen before include "Big - - , WW1 gun" , "Big ..., heavy German howitzer in World War 1" , "Female name; Big -, World War one German howitzer" , "Girl's name - big German WWI gun" , "Big girl" .)