Feel sentence provides a boundary (9)
I believe the answer is:
touchline
'a boundary' is the definition.
The answer and definition can be both locations as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'feel sentence' is the wordplay.
'feel' becomes 'touch' (touching is a kind of feeling).
'sentence' becomes 'line' (I am not sure about this - if you are sure you should believe this answer much more).
'touch'+'line'='TOUCHLINE'
'provides' is the link.
Can you help me to learn more?
(Other definitions for touchline that I've seen before include "side of pitch" , "Rugby/soccer pitch marking" .)