First of hurdlers entering slowest heat, surprisingly, be the best (5,3,4)
I believe the answer is:
steal the show
'the best' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'first of hurdlers entering slowest heat surprisingly' is the wordplay.
'first of' suggests taking the first letters.
'entering' means one lot of letters goes inside another.
'surprisingly' is an anagram indicator.
The initial letter of 'hurdlers' is 'h'.
'slowest'+'heat'='slowestheat'
'slowestheat' anagrammed gives 'stealteshow'.
'h' inserted into 'stealteshow' is 'STEAL THE SHOW'.
'be' is the link.
Can you help me to learn more?
(Other definitions for steal the show that I've seen before include "Draw most attention and praise" , "capture everyone's attention" , "Attract the most attention and praise" , "Unexpectedly attract the most applause" , "Attract the most admiration" .)