Attention later moved to head (9)
I believe the answer is:
alertness
'attention' is the definition.
(I know that alertness is a type of attention)
'later moved to head' is the wordplay.
'moved' indicates an anagram.
'to head' becomes 'ness' (ness is a headland).
'later' anagrammed gives 'alert'.
'alert'+'ness'='ALERTNESS'
(Other definitions for alertness that I've seen before include "It's needed to respond quickly to danger" , "Showing attentive nature" , "State of vigilance and watchfulness" , "Watchful state" , "Wakeful characteristic" .)