Being considered in case daughter must tap into reserve energy (3,6)
I believe the answer is:
sub judice
'being considered in case' is the definition.
(in court, from Latin for 'under judgment')
'daughter must tap into reserve energy' is the wordplay.
'daughter' becomes 'd'.
'must tap into' indicates putting letters inside.
'reserve' becomes 'sub' (I've seen this in other clues).
'energy' becomes 'juice' (I've seen this before).
'sub'+'juice'='subjuice'
'd' placed into 'subjuice' is 'SUB JUDICE'.
(Other definitions for sub judice that I've seen before include "Under consideration by court - don't comment" , "Under consideration by the courts - don't comment on it" , "Still before court" .)