Shipbuilder dropping into Bath regularly (4)
I believe the answer is:
noah
'shipbuilder' is the definition.
(I have seen 'Biblical shipbuilder' mean 'noah' so perhaps 'shipbuilder' could also mean 'noah')
'into bath regularly' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'into'+'bath'='intobath'
The alternating letters of 'intobath' are 'NOAH'.
'dropping' is the link.
This may not be right. It may be part of another bit of the clue.
(Other definitions for noah that I've seen before include "Biblical boat builder" , "Biblical skipper during the Flood" , "Biblical patriarch" , "Biblical arkwright" , "Animal rescuer" .)