Designer Helmut (4)
I believe the answer is:
lang
'designer helmut' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lang that I've seen before include "Austrian-born film director" , "Traditional Scottish song 'Auld . . . . Syne'" , "Old song 'Auld . . . . Syne'" .)