Regularly applauds bonus (4)
I believe the answer is:
plus
'bonus' is the definition.
(I've seen this before)
'regularly applauds' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
The alternating letters of 'applauds' are 'PLUS'.
(Other definitions for plus that I've seen before include "mark for arithmetic" , "being a little cross" , "The opposite of minus" , "Additional" , "As well as" .)