Arrived to collect old university standard in disguise (10)
I believe the answer is:
camouflage
'disguise' is the definition.
(I know that disguise can be written as camouflage)
'arrived to collect old university standard' is the wordplay.
'arrived' becomes 'came' (come can mean to appear or arrive).
'to collect' means one lot of letters goes inside another (inserted letters are collected by others).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'university' becomes 'U' (abbreviation for university).
'standard' becomes 'flag' (standard is a type of flag).
'o'+'u'+'flag'='ouflag'
'came' going around 'ouflag' is 'CAMOUFLAGE'.
'in' is the link.
(Other definitions for camouflage that I've seen before include "Method of blending in fine" , "blind" , "Green and brown on a green and brown background, say?" , "Disguise (from enemy)" , "Means of disguise" .)