Studied article in colour (4)
I believe the answer is:
read
'studied' is the definition.
(to read a subject is to study it at university)
'article in colour' is the wordplay.
'article' becomes 'a' (English indefinite article).
'in' means one lot of letters goes inside another.
'colour' becomes 'red' (red is a kind of colour).
'a' placed within 'red' is 'READ'.
(Other definitions for read that I've seen before include "Studied" , "Absorbed (written text)" , "what follows 18 [OMASUM] in a 17 [RUMINANT]" , "Check, emend (proof)" , "Stomach" .)