Old poetry university dons do to death (7)
I believe the answer is:
overuse
'do to death' is the definition.
'old poetry university dons' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'poetry' becomes 'verse' (synonyms).
'university' becomes 'u' (abbreviation for university).
'dons' means one lot of letters goes inside another (inserted letters wear or 'don' others).
'verse' placed around 'u' is 'veruse'.
'o'+'veruse'='OVERUSE'
(Other definitions for overuse that I've seen before include "Excessive (drug) taking" , "Excessive employment" , "Employ too often" , "why injury may occur" , "Employ too much" .)