Homeless child would appear in front, first of all (4)
I believe the answer is:
waif
'homeless child' is the definition.
(I've seen this before)
'would appear in front first of all' is the wordplay.
'first of all' indicates taking the first letters.
The first letters of 'would appear in front' is 'WAIF'.
(Other definitions for waif that I've seen before include "Be incongruous" , "Someone very thin or underfed" , "Orphan" , "neglected issue" , "Gamin" .)