Stop regularly, as it seems (4)
I believe the answer is:
stem
'stop' is the definition.
(stemming is a kind of stopping)
'regularly as it seems' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'as'+'it'+'seems'='asitseems'
The alternating letters of 'asitseems' are 'STEM'.
(Other definitions for stem that I've seen before include "Axis" , "Slender vertical part, glass or plant" , "Tube" , "Halt flow" , "Check - part of a plant" .)