Expression of disapproval at uniform skirt (4)
I believe the answer is:
tutu
'skirt' is the definition.
(tutu is a kind of skirt)
'expression of disapproval at uniform' is the wordplay.
'expression of disapproval' becomes 'tut' (I've seen this before).
'at' is a charade indicator (letters next to each other).
'uniform' becomes 'u' (phonetic alphabet: alpha, bravo, charlie etc.).
'tut'+'u'='TUTU'
(Other definitions for tutu that I've seen before include "The old primate" , "outfit" , "Ballerina's costume" , "8 [BALLET] term" , "Giselle's skirt" .)