Chairmen regularly feel concern (4)
I believe the answer is:
care
'feel concern' is the definition.
('care' can be a synonym of 'feel concern')
'chairmen regularly' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
The alternate letters of 'chairmen' are 'CARE'.
(Other definitions for care that I've seen before include "Prudence" , "Caution; keeping" , "Worry" , "Protective custody" , "Happy-go-lucky" .)