Required Scots hooligan to cross rising river (6)
I believe the answer is:
needed
'required' is the definition.
(I know that required can be written as needed)
'scots hooligan to cross rising river' is the wordplay.
'scots hooligan' becomes 'ned' (Scottish term for a hooligan).
'to cross' indicates putting letters inside.
'rising' says the letters should be written backwards (going up in a down clue).
'river' becomes 'Dee' (River Dee).
'dee' backwards is 'eed'.
'ned' going around 'eed' is 'NEEDED'.
(Other definitions for needed that I've seen before include "Missing" , "Was in want of" , "Required something essential" , "Required; sounds like worked (dough)" , "'Wanted, required (6)'" .)