Mother takes a long time obtaining reparation (7)
I believe the answer is:
damages
'reparation' is the definition.
(thesaurus)
'mother takes a long time' is the wordplay.
'mother' becomes 'dam' (female parent of an animal).
'takes' means one lot of letters go next to another.
'a long time' becomes 'ages' (ages can mean a very long time).
'dam'+'ages'='DAMAGES'
'obtaining' is the link.
(Other definitions for damages that I've seen before include "Harms" , "Hurts" , "Moneys paid as compensation for an injury" , "Money awarded as compensation" , "weakens" .)