Spread out, once looked after (8)
I believe the answer is:
extended
'spread out' is the definition.
(thesaurus)
'once looked after' is the wordplay.
'once' becomes 'ex'.
'looked after' becomes 'tended' (tending is a kind of looking after).
'ex'+'tended'='EXTENDED'
(Other definitions for extended that I've seen before include "Stretched out over time or space" , "Protracted, elongated" , "Stretched, drew out" , "Stretched or reached out - the hand of friendship? (8)" , "Lengthy" .)