Russian girl in gaol break (4)
I believe the answer is:
olga
'russian girl' is the definition.
(I've seen this before)
'gaol break' is the wordplay.
'break' is an anagram indicator.
'gaol' anagrammed gives 'OLGA'.
'in' acts as a link.
(Other definitions for olga that I've seen before include "Slavic girl's name" , "Could be Russian girl" , "Lady" , "Russian girl's name, anagram of ..." .)