Waterside walk wife visits to caress horse (7)
I believe the answer is:
towpath
'waterside walk' is the definition.
(walkway by a canal)
'wife visits to caress horse' is the wordplay.
'wife' becomes 'w'.
'visits' indicates putting letters inside (visit can mean to go into).
'caress' becomes 'pat' (patting is a kind of caressing).
'horse' becomes 'H' (synonyms).
'to'+'pat'='topat'
'w' put into 'topat' is 'towpat'.
'towpat'+'h'='TOWPATH'
(Other definitions for towpath that I've seen before include "Waterside track for horses" , "Way beside a canal" , "Walkway beside canal" , "Canal-side walkway" , "22 by canal" .)