Cause to get son somewhere to settle (5)
I believe the answer is:
roost
'settle' is the definition.
(roosting is a kind of settling)
'cause to get son' is the wordplay.
'cause' becomes 'root' (as in a root cause).
'to get' means one lot of letters goes inside another.
'son' becomes 's' (genealogical abbreviation for son).
'root' going around 's' is 'ROOST'.
'somewhere to' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for roost that I've seen before include "Place where birds perch or settle for sleep" , "Bird's shelter" , "Henhouse" , "Temporary place to stay" , "somewhere to sleep" .)