Regret the absence of the girl (4)
I believe the answer is:
miss
This clue is a triple definition!
'regret' is the first definition.
(I know that regret is a more specific form of the action miss)
'the absence' is the second definition.
(thesaurus)
'of' is a link.
'the girl' is the third definition.
(term of address for an unmarried woman)
(Other definitions for miss that I've seen before include "Fail to find" , "Fail to hit (the target)" , "Agatha Christie's detective" , "Suffer from the lack of" , "Girl or unmarried woman" .)