Balkan woman upset about long trousers (8)
I believe the answer is:
britches
'trousers' is the definition.
(britches is a kind of trousers)
'balkan woman upset about long' is the wordplay.
'balkan woman' becomes 'serb' (Serb is an example).
'upset' says the letters should be written in reverse.
'about' means one lot of letters goes inside another.
'long' becomes 'itch' (I've seen this before).
'serb' in reverse letter order is 'bres'.
'bres' placed around 'itch' is 'BRITCHES'.
(Other definitions for britches that I've seen before include "American garment" , "Trousers" , "Garb for Yanks" .)