One cell prepared for an Irish girl (7)
I believe the answer is:
colleen
'an irish girl' is the definition.
(I've seen this before)
'one cell prepared' is the wordplay.
'prepared' is an anagram indicator.
'one'+'cell'='onecell'
'onecell' anagrammed gives 'COLLEEN'.
'for' acts as a link.
(Other definitions for colleen that I've seen before include "Irish girl, English version" , "Irish lass" , "Young Irish woman" , "Find Irish girl in cell one" , "Irish miss" .)