Yearn to get top athlete (4,6)
I believe the answer is:
long jumper
'athlete' is the definition.
(I've seen this before)
'yearn to get top' is the wordplay.
'yearn' becomes 'long' (synonyms).
'to get' says to put letters next to each other.
'top' becomes 'jumper' (I've seen this before).
'long'+'jumper'='LONG JUMPER'
(Other definitions for long jumper that I've seen before include "what covers his or her thighs?" , "Athlete" , "one that can touch his knees?" , "garment that comes down over the thighs?" .)