One walked across, resolving to get rid of BO? (10)
I believe the answer is:
footbridge
'one walked across' is the definition.
(something people walk across)
'resolving to get rid of bo?' is the wordplay.
'resolving to' indicates anagramming the letters (the anagram resolves to another word).
'get'+'rid'+'of'+'bo'='getridofbo'
'getridofbo' with letters rearranged gives 'FOOTBRIDGE'.
(Other definitions for footbridge that I've seen before include "unsuitable for the motorist?" , "walkway" , "Pedestrian crossing, as it were" , "Over which one may walk" .)