When hot, follows Latin beat (4)
I believe the answer is:
lash
'beat' is the definition.
(lashing is a kind of beating)
'when hot follows latin' is the wordplay.
'when' becomes 'as'.
'hot' becomes 'h' (abbreviation eg on taps).
'follows' says to put letters next to each other.
'latin' becomes 'l'.
'as'+'h'='ash'
'ash' put after 'l' is 'LASH'.
(Other definitions for lash that I've seen before include "Birch" , "cat hair?" , "Strike with a whip" , "Flog" , "Bind tightly with a rope or cord" .)