Bulletins about horse in training those my sister gave me? (7)
I believe the answer is:
nephews
'those my sister gave me?' is the definition.
I can't tell whether this defines the answer.
'bulletins about horse in training' is the wordplay.
'bulletins' becomes 'news' (I can't justify this - if you can you should believe this answer much more).
'about' indicates putting letters inside.
'horse' becomes 'H' (abbreviation as in horse power).
'in' is an insertion indicator.
'training' becomes 'PE' (short for Physical Education).
'h' placed within 'pe' is 'phe'.
'news' enclosing 'phe' is 'NEPHEWS'.
Can you help me to learn more?
(Other definitions for nephews that I've seen before include "Male relatives" , "Kinsmen" , "Male kin" .)