Check part of tobacco pipe (4)
I believe the answer is:
stem
I believe this clue is a double definition.
'check' is the first definition.
(I've seen this before)
'part of tobacco pipe' is the second definition.
('stem' is part of 'tobacco pipe')
(Other definitions for stem that I've seen before include "Type of cell" , "Slender upright part of wine glass" , "Upward part of a plant" , "Thwart; support" , "Vertical part of flower or drinking glass" .)