Very few regularly watch (3)
I believe the answer is:
eye
'watch' is the definition.
(I've seen this before)
'very few regularly' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'very'+'few'='veryfew'
The alternate letters of 'veryfew' are 'EYE'.
(Other definitions for eye that I've seen before include "Aim for" , "Keep watch on" , "Perception" , "round hole in sewer?" , "'Public' or 'private' body part" .)