Some birds love to get instruction in developing chests (9)

I believe the answer is:
ostriches
'some birds' is the definition.
(ostrich is a kind of bird)
'love to get instruction in developing chests' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'to get instruction' becomes 'ri' (I can't explain this - if you can you should believe this answer much more).
'in' means one lot of letters goes inside another.
'developing' indicates an anagram (letters developed into a new form).
'chests' with letters rearranged gives 'stches'.
'ri' put into 'stches' is 'striches'.
'o'+'striches'='OSTRICHES'
Can you help me to learn more?
(Other definitions for ostriches that I've seen before include "People not facing the reality" , "Fast-running flightless birds" , "Largest living birds" .)
