Lack of energy — it leads us astray (9)
I believe the answer is:
lassitude
'lack of energy' is the definition.
(I've seen this before)
'it leads us astray' is the wordplay.
'astray' indicates anagramming the letters.
'it'+'leads'+'us'='itleadsus'
'itleadsus' anagrammed gives 'LASSITUDE'.
(Other definitions for lassitude that I've seen before include "Sluggishness" , "Is saluted with tiredness" , "Weariness" , "Listlessness, state of apathy" , "Listlessness, fatigue" .)