On the street, this horse takes a bit of feeding! (5)
I believe the answer is:
steed
'on the street this horse takes a bit of feeding' is the definition.
'steed' can be an answer for 'horse' (steed is a kind of horse). I am not certain of the rest of the definition.
'horse takes a bit of feeding' is the wordplay.
'horse' becomes 'seed' (I can't justify this - if you can you should give a lot more credence to this answer).
'a bit of' indicates taking the first letters.
'feeding' indicates putting letters inside (one word is fed by another set of letters).
The initial letter of 'takes' is 't'.
'seed' enclosing 't' is 'STEED'.
Can you help me to learn more?
(Other definitions for steed that I've seen before include "Swift horse" , "ride" , "Powerful horse" , "Stallion" , "(Poetic) horse" .)