White-haired Scottish cyclist crossing American river (5)
I believe the answer is:
hoary
'white-haired' is the definition.
(thesaurus)
'cyclist crossing american river' is the wordplay.
'cyclist' becomes 'hoy' (Sir Chris Hoy).
'crossing' indicates putting letters inside (to cross can mean to go over or around).
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'river' becomes 'r' (abbreviation).
'a'+'r'='ar'
'hoy' placed around 'ar' is 'HOARY'.
'scottish' acts as a link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for hoary that I've seen before include "Frosty" , "Venerably grey" , "Grey-haired and old" , "Grizzly - ancient" , "White or grey with age" .)