In component of bathometer (2,4)
I believe the answer is:
at home
'in' is the definition.
'component of bathometer' is the wordplay.
'component of' says the answer is hidden in the clue (I've seen this in other clues).
'AT-HOME' is hidden in the letters of 'bathometer'.
(Other definitions for at home that I've seen before include "ready to receive visitors" , "Comfortable - in one's own country" , "Where one lives" , "In one's own house" , "Reception in one's own abode" .)