Nurse in warm bath regularly (4)
I believe the answer is:
amah
'nurse' is the definition.
(amah is a kind of nurse)
'warm bath regularly' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'warm'+'bath'='warmbath'
The alternating letters of 'warmbath' are 'AMAH'.
'in' acts as a link.
(Other definitions for amah that I've seen before include "Old Asian maid" , "Chinese nursemaid" , "Maid serving" , "Asian nursemaid" , "nurse from abroad" .)