Pressure university head to wear gown (6)
I believe the answer is:
duress
'pressure' is the definition.
(I've seen this before)
'university head to wear gown' is the wordplay.
'head to' says to take the initial letters (I've seen 'heading to' mean this).
'wear' means one lot of letters goes inside another (to wear something is to be covered up by it).
'gown' becomes 'dress' (gown is a kind of dress).
The initial letter of 'university' is 'u'.
'u' inserted within 'dress' is 'DURESS'.
(Other definitions for duress that I've seen before include "Compulsion by use of force" , "Compulsory force or threat" , "Force, coercion" , "Constraint, Compulsion" , "Pressure applied by druses" .)