Crossed river wearing a vest and red pants (9)
I believe the answer is:
traversed
'crossed' is the definition.
('traverse' can be a synonym of 'cross')
'river wearing a vest and red pants' is the wordplay.
'river' becomes 'r' (abbreviation for river).
'wearing' is an insertion indicator.
'and' is a charade indicator (letters next to each other).
'pants' is an anagram indicator (UK informal term for 'nonsense' or 'rubbish').
'a'+'vest'+'red'='avestred'
'avestred' with letters rearranged gives 'taversed'.
'r' put into 'taversed' is 'TRAVERSED'.
(Other definitions for traversed that I've seen before include "Came across" , "passed over" , "Crossed" , "Went over" , "Travelled across zigzag course" .)