Felt sorry corralling horse that's difficult (6)
I believe the answer is:
rugged
'difficult' is the definition.
(thesaurus)
'felt sorry corralling horse' is the wordplay.
I cannot quite understand how this works, but
'horse' could be 'gg' (geegee or GG is a childish term for a horse) and 'gg' is found within the answer.
'felt' could be 'rued' (ruing is a kind of feeling) and 'rued' is present in the leftover letters.
No letters remain.
This explanation may well be incorrect...
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for rugged that I've seen before include "Rough and harsh" , "wearing a wig?" , "Rocky - rough - hard" , "Sturdy, strong and enduring" , "designed for heavy use" .)