Queue behind small child where vagrants congregate? (4,3)
I believe the answer is:
skid row
'where vagrants congregate?' is the definition.
(part of a town where vagrants gather)
'queue behind small child' is the wordplay.
'queue' becomes 'row'.
'behind' means one lot of letters go next to another.
'small' becomes 's' (abbreviation - e.g. clothes size).
'child' becomes 'kid' (synonyms).
's'+'kid'='skid'
'row' put after 'skid' is 'SKID ROW'.
(Other definitions for skid row that I've seen before include "bad part of town" , "it's the way of many drunks" , "Run-down part of town (mainly US)" , "US slum" , "Run-down part of US town frequented by vagrants" .)