Though varying in cut, is usually uniform (5)
I believe the answer is:
tunic
'usually uniform' is the definition.
'tunic' can be an answer for 'uniform' (I have seen 'Military uniform' mean 'tunic' so perhaps 'uniform' could also mean 'tunic'). I'm not certain of the 'usually' bit.
'though varying in cut' is the wordplay.
'though' becomes 'tuc' (I am not sure about this - if you are sure you should believe this answer much more).
'varying' is an anagram indicator.
'cut' is an insertion indicator (some letters cut their way into a word).
'in' is an anagram of 'ni'.
'tuc' going around 'ni' is 'TUNIC'.
'is' is the link.
Can you help me to learn more?
(Other definitions for tunic that I've seen before include "(Policeman's) jacket" , "Schoolgirl's dress" , "Upper garment, for a soldier say" , "Clobber" , "Policeman may be in one" .)