Fast runner I caught in short burst (7)
I believe the answer is:
ostrich
'fast runner' is the definition.
'ostrich' can be an answer for 'runner' (I've seen this before). I am unsure of the 'fast' bit.
'i caught in short burst' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'in' indicates putting letters inside.
'burst' indicates an anagram.
'i'+'c'='ic'
'short' with letters rearranged gives 'ostrh'.
'ic' going into 'ostrh' is 'OSTRICH'.
Can you help me to learn more?
(Other definitions for ostrich that I've seen before include "Largest extant bird" , "Emu-like bird" , "Bird burying its head in the sand" , "Long-necked bird" , "Nut-burying type" .)