Crossword Genius

Regularly saw firms dip (4)

Ross

I believe the answer is:

swim

'dip' is the definition.
(I've seen this in another clue)

'regularly saw firms' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'saw'+'firms'='sawfirms'
The alternating letters of 'sawfirms' are 'SWIM'.

(Other definitions for swim that I've seen before include "Bathe" , "Do the dog paddle, perhaps" , "Move through the water - be dizzy" , "German submarine" , "Do crawl, perhaps" .)

I've seen this clue in The Guardian.
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