Daughter with bad back and slouch (5)
I believe the answer is:
droop
'slouch' is the definition.
(thesaurus)
'daughter with bad back' is the wordplay.
'daughter' becomes 'd'.
'with' says to put letters next to each other.
'bad' becomes 'poor' (similar in meaning).
'back' shows that the letters should be reversed in order.
'poor' written backwards gives 'roop'.
'd'+'roop'='DROOP'
'and' is the link.
(Other definitions for droop that I've seen before include "Sag wearily" , "Go limp" , "Hang down loosely" , "languish" , "male problem?" .)