Fine even Rachel, surprisingly, for unauthorised absence (6,5)
I believe the answer is:
french leave
'unauthorised absence' is the definition.
(I've seen this before)
'fine even rachel surprisingly' is the wordplay.
'fine' becomes 'f' (abbreviation).
'surprisingly' indicates an anagram.
'even'+'rachel'='evenrachel'
'evenrachel' with letters rearranged gives 'renchleave'.
'f'+'renchleave'='FRENCH LEAVE'
'for' is the link.
(Other definitions for french leave that I've seen before include "just slipping away" , "Unauthorised absence from work" , "Holiday in Provence perhaps" , "Absence without permission" .)