Type of water bath (4)
I believe the answer is:
font
'type of water bath' is the definition.
'font' can be an answer for 'type' (font is a kind of type). I am unsure of the 'of water bath' bit.
'type of water bath' is the wordplay.
'type' indicates an anagram.
'water bath' becomes 'nt' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'of' with letters rearranged gives 'fo'.
'fo'+'nt'='FONT'
Can you help me to learn more?
(Other definitions for font that I've seen before include "Size and style of type" , "Baptismal basin" , "Well" , "Vessel for baptismal water" , "Baptismal bowl" .)