One gets in the bath, perhaps, as a regular thing (5)
I believe the answer is:
habit
'a regular thing' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe there's a link between them I don't understand?
'one gets in the bath perhaps' is the wordplay.
'one' becomes 'i' (Roman numeral).
'gets in' means one lot of letters goes inside another.
'perhaps' indicates anagramming the letters.
'bath' is an anagram of 'habt'.
'i' put within 'habt' is 'HABIT'.
'as' acts as a link.
Can you help me to learn more?
(Other definitions for habit that I've seen before include "Riding garment" , "Custom; clothing" , "Settled practice" , "Routine - clothing" , "Custom or monk's robe" .)