Soak fruit one sister's put on (8)
I believe the answer is:
inundate
'soak' is the definition.
(thesaurus)
'fruit one sister's put on' is the wordplay.
'fruit' becomes 'date' (date is a kind of fruit).
'one' becomes 'i' (Roman numeral).
'sister' becomes 'nun' (I've seen this before).
'put on' says to put letters next to each other.
'i'+'nun'='inun'
'date' put after 'inun' is 'INUNDATE'.
(Other definitions for inundate that I've seen before include "Flood - and unite (anag)" , "be overwhelming" , "Flood, overwhelm" , "Overwhelm with things to be done" , "Overwhelm, swamp" .)