Cheer, having involved university investigators to explain (9)
I believe the answer is:
elucidate
'explain' is the definition.
(elucidating is a kind of explaining)
'cheer having involved university investigators' is the wordplay.
'cheer' becomes 'elate' (to elate is to cheer or make happy).
'having' indicates putting letters inside.
'involved university' becomes 'u' (abbreviation as in UMass. I am not sure about the 'involved' bit.).
'investigators' becomes 'CID' (Criminal Investigation Department).
'u'+'cid'='ucid'
'elate' going around 'ucid' is 'ELUCIDATE'.
'to' is the link.
Can you help me to learn more?
(Other definitions for elucidate that I've seen before include "Make clear and more comprehensible" , "Make clear, explain" , "Throw light on a problem, make clear (9)" , "Shed light upon" , "Shed light on, clarify" .)