Son in digs bringing in girl for sport (13)
I believe the answer is:
skateboarding
'sport' is the definition.
(skateboarding is a kind of sport)
'son in digs bringing in girl' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'in digs' becomes 'boarding' (I can't justify this - if you can you should give a lot more credence to this answer).
'bringing in' means one lot of letters goes inside another.
'girl' becomes 'kate' (girl's name).
's'+'boarding'='sboarding'
'sboarding' enclosing 'kate' is 'SKATEBOARDING'.
'for' is the link.
Can you help me to learn more?
(Other definitions for skateboarding that I've seen before include "Teenagers' pastime" , "Wheeled recreation" , "sport" , "recreational activity" , "Pastime on wheels" .)