University moved fast, initially isolating unruly male element (7)
I believe the answer is:
uranium
'element' is the definition.
(I know that uranium is a type of metal)
'university moved fast initially isolating unruly male' is the wordplay.
'university' becomes 'u' (abbreviation for university).
'moved fast' becomes 'ran' (I've seen this before).
'initially' suggests taking the first letters.
The first letters of 'isolating unruly male' is 'ium'.
'u'+'ran'+'ium'='URANIUM'
(Other definitions for uranium that I've seen before include "Radioactive element of atomic number 92" , "Radioactive metal, atomic number 92" , "Radioactive element used for nuclear energy" , "Radioactive material" , "Fissile element" .)