Very corrupt senior type (7)
I believe the answer is:
version
'type' is the definition.
(version is a kind of type)
'very corrupt senior' is the wordplay.
'very' becomes 'v' (abbreviation).
'corrupt' indicates an anagram.
'senior' is an anagram of 'ersion'.
'v'+'ersion'='VERSION'
(Other definitions for version that I've seen before include "Sort" , "Interpretation, account" , "Account from one point of view" , "Adaptation" , "Translation - personal account" .)