Dress up first in compulsion (6)
I believe the answer is:
duress
'compulsion' is the definition.
(thesaurus)
'dress up first in' is the wordplay.
'first' suggests taking the first letters.
'in' indicates putting letters inside.
The initial letter of 'up' is 'u'.
'dress' placed around 'u' is 'DURESS'.
(Other definitions for duress that I've seen before include "Use of force or threats to get something" , "Hardship" , "Use of force or threats, often vile" , "Compulsory force or threat" , "Pressure (involving threats)" .)