Son immediately gets cold shower (4)
I believe the answer is:
snow
'cold shower' is the definition.
(I've seen this in another clue)
'son immediately' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'immediately' becomes 'now' (I've seen this in another clue).
's'+'now'='SNOW'
'gets' is the link.
(Other definitions for snow that I've seen before include "Wintry stuff" , "Precipitation in the form of ice crystals" , "feature of 27 [THE BIG FREEZE]" , "Wintry flakes?" , "It falls in flakes" .)