Small child having irregular rest risks falling down (7)
I believe the answer is:
totters
'risks falling down' is the definition.
(to totter is to be in danger of falling)
'small child having irregular rest' is the wordplay.
'small child' becomes 'tot' (I've seen this before).
'having' is a charade indicator (letters next to each other).
'irregular' is an anagram indicator.
'rest' is an anagram of 'ters'.
'tot'+'ters'='TOTTERS'
(Other definitions for totters that I've seen before include "Scrap dealers" , "salvage-collectors" , "rocks" , "proceeds uncertainly" , "Walks unsteadily" .)