Make more extensive (5)
(Other definitions for widen that I've seen before include "Edwin (anag)" , "Extend across" , "Spread" , "Increase dimension" , "Broaden - enlarge" .)
(Other definitions for enlarge that I've seen before include "Broaden, increase" , "Dilate" , "Blow up" , "go into greater detail" , "Expand" .)