University home given external colour and spoilt (6)
I believe the answer is:
ruined
'spoilt' is the definition.
(ruining is a kind of spoiling)
'university home given external colour' is the wordplay.
'university' becomes 'u'.
'home' becomes 'in' ('he's home' can mean 'he's in').
'given external' indicates putting letters inside.
'colour' becomes 'red' (red is a kind of colour).
'u'+'in'='uin'
'uin' put within 'red' is 'RUINED'.
'and' acts as a link.
(Other definitions for ruined that I've seen before include "Done for" , "Utterly destroyed" , "Broke" , "Destroyed or bankrupted" , "Wrecked" .)