Investigated and turned up modern colour, then old (4,4)
I believe the answer is:
went into
'investigated' is the definition.
(to go into something is to investigate it)
'turned up modern colour then old' is the wordplay.
'turned up' is a reversal indicator.
'modern' becomes 'new' (associated in meaning).
'colour then old' becomes 'tinto' (I can't justify this - if you can you should believe this answer much more).
'new' backwards is 'wen'.
'wen'+'tinto'='WENT INTO'
'and' is the link.
(Other definitions for went into that I've seen before include "investigated" , "Discussed" , "Entered" .)