Inferior supporter precedes superior (6,4)
I believe the answer is:
second best
'inferior' is the definition.
(I've seen this before)
'supporter precedes superior' is the wordplay.
I cannot quite see how this works, but
'supporter' could be 'second' (second is a kind of supporter) and 'second' is present in the answer.
'superior' could be 'best' (associated in meaning) and 'best' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for second best that I've seen before include "not quite good enough" , "footballer Man U would like on their books?" , "not so great?" , "substitute not quite in the top bracket?" , "new Manchester United whizz kid?" .)