Cylindrical bath and foundation overlap (5)

I believe the answer is:

tubed

'cylindrical' is the definition.

'bath and foundation overlap' is the wordplay.
'bath' becomes 'tub' (synonyms).
'and' means one lot of letters go next to another.
'foundation overlap' becomes 'ed' (I am not sure about this - if you are sure you should believe this answer much more).
'tub'+'ed'='TUBED'

(Another definition for tubed that I've seen is " on the underground?".)

I've seen this clue in The Independent.

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