Lean minor lacking energy (8)
I believe the answer is:
listless
'lacking energy' is the definition.
(I've seen this before)
'lean minor' is the wordplay.
'lean' becomes 'list' (both can mean to tilt).
'minor' becomes 'less' (I've seen this before).
'list'+'less'='LISTLESS'
(Other definitions for listless that I've seen before include "Lacking zest or vivacity" , "Languid - apathetic" , "Short of energy (and ill-equipped for shopping?)" , "Devoid of energy or concern" , "Lacking energy or vitality" .)