Sit astride and go off, following street on right (8)
I believe the answer is:
straddle
'sit astride' is the definition.
(I've seen this before)
'go off following street on right' is the wordplay.
'go off' becomes 'addle' (eg an egg might addle**).
'following' is a charade indicator (letters next to each other).
'street' becomes 'st'.
'on' says to put letters next to each other.
'right' becomes 'r' (common abbreviation).
'st'+'r'='str'
'addle' put after 'str' is 'STRADDLE'.
'and' is the link.
(Other definitions for straddle that I've seen before include "Stand with legs wide apart" , "Span" , "Get over" , "Extend over a certain area" , "Bestride" .)