Partner hiding hairstyle until it goes dark? (3-3)
I believe the answer is:
all-day
'until it goes dark?' is the definition.
(all day but not at night)
'partner hiding hairstyle' is the wordplay.
'partner' becomes 'ally' (I've seen this in another clue).
'hiding' is an insertion indicator.
'hairstyle' becomes 'DA' (duck's arse, a950s hairstyle).
'ally' enclosing 'da' is 'ALL-DAY'.
(Other definitions for all-day that I've seen before include "In unhurried manner" , "Twenty-four-hour" , "From dawn to dusk" , "Lasting twentty four hours" .)