Second son in Cambridge colleges area (5)
I believe the answer is:
backs
'cambridge colleges area' is the definition.
I can't tell whether this definition defines the answer.
'second son' is the wordplay.
'second' becomes 'back' (to second a motion is to back it).
'son' becomes 's' (genealogical abbreviation for son).
'back'+'s'='BACKS'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for backs that I've seen before include "delightful Cambridge area" , "Helps or supports with money" , "Defenders" , "champions" , "Defensive players" .)