Uniform in attire in force (6)
I believe the answer is:
duress
'force' is the definition.
(I know that duress is a type of force)
'uniform in attire' is the wordplay.
I cannot quite understand how this works, but
'uniform' could be 'u' (phonetic alphabet: alpha, bravo, charlie etc.) and 'u' is located in the answer.
'attire' could be 'dress' (synonyms) and 'dress' is located in the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Other definitions for duress that I've seen before include "Use of force or threats, often vile" , "Force, coercion" , "Illegal coercion" , "Constraint, Compulsion" , "Constraint, coercion" .)