Now and then Croatians spit, possibly ... (4)
I believe the answer is:
rain
'spit possibly' is the definition.
'rain' can be an answer for 'spit' (thesaurus). I'm unsure of the 'possibly' bit.
'now and then croatians' is the wordplay.
'now and then' means one should take alternating letters (letters taken on a regular basis, now and then).
The alternate letters of 'croatians' are 'RAIN'.
Can you help me to learn more?
(Other definitions for rain that I've seen before include "eg A shower" , "Pelt" , "The right" , "Precipitation" , "previous rule?" .)