Sketched daybreak across river (5)
I believe the answer is:
drawn
'sketched' is the definition.
(I've seen this in another clue)
'daybreak across river' is the wordplay.
'daybreak' becomes 'dawn' (synonyms).
'across' is an insertion indicator.
'river' becomes 'r' (abbreviation for river).
'dawn' enclosing 'r' is 'DRAWN'.
(Other definitions for drawn that I've seen before include "Closed" , "(Of a face) showing evidence of strain" , "Picked" , "Sketched; pulled" , "tense" .)