Biblical character called up to cross lake (7)
I believe the answer is:
delilah
'biblical character' is the definition.
(I've seen this before)
'called up to cross lake' is the wordplay.
'called' becomes 'hailed' (hailing is a kind of calling).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'to cross' is an insertion indicator.
'lake' becomes 'L' (geographical abbreviation).
'hailed' written backwards gives 'deliah'.
'deliah' placed around 'l' is 'DELILAH'.
(Other definitions for delilah that I've seen before include "Biblical temptress" , "Tom Jones song" , "Seductive woman" , "Siren" , "She sheared Samson" .)