Certain kids jostled for favourable position (6,5)
I believe the answer is:
inside track
'favourable position' is the definition.
'inside track' can be an answer for 'position' (I have seen 'Advantageous position' mean 'inside track' so perhaps 'position' could also mean 'inside track'). I'm not certain of the 'favourable' bit.
'certain kids jostled' is the wordplay.
'jostled' is an anagram indicator (I've seen this in other clues).
'certain'+'kids'='certainkids'
'certainkids' anagrammed gives 'INSIDE TRACK'.
'for' is the link.
Can you help me to learn more?
(Other definitions for inside track that I've seen before include "Most advantageous side of race course" , "last song on the LP?" , "Advantageous position" , "In a position of advantage" .)