Finding streets in the Canada 1921 Census (especially for Toronto) has been discussed in an earlier question.
As I wasn't able to find a street index, I compilied a partial one from the descriptions Ancestry supplied for some subdistricts. It doesn't include streets where the subdistrict contains more than one polling subdivision, which is especially common in Toronto North. Still, it's better than nothing. As mentioned in my answer to my question there, this partial index is available on Github. Improvements and corrections welcome!
It contains the following entries for Clinton St:
Clinton St. both sides, from Mansfield avenue to College Street: Sub-District 41 - Ward 5 : Toronto West
Clinton Street, both sides, from College to Harbord Street: Sub-District 57 - Ward 5 : Toronto West
Clinton Street, east side, from Harbord to Bloor Street: Sub-District 58 - Ward 5 : Toronto West
Clinton Street, west side, from Harbord to Bloor Street.: Sub-District 65 - Ward 5 : Toronto West
Again, there may be other sections of the street that it does not list, because they are not described in the Ancestry descriptions.