Philosopher's son argues from time to time (4)
I believe the answer is:
sage
'philosopher's' is the definition.
(sage can mean a wise person)
'son argues from time to time' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'from time to time' means one should take alternating letters (letters removed on a regular basis).
The alternate letters of 'argues' are 'age'.
's'+'age'='SAGE'
(Other definitions for sage that I've seen before include "Wise green herb?" , "Wise man - flavoursome plant" , "Clever" , "Fragrant herb or wise man" , "Feature of herb garden" .)