Fit shelves evenly in loft (8)
I believe the answer is:
athletic
'fit' is the definition.
(I've seen this before)
'shelves evenly in loft' is the wordplay.
'evenly' indicates alternate letters (the letters in even-numbered positions).
'in' indicates putting letters inside.
'loft' becomes 'attic' (synonyms).
The alternate letters of 'shelves' are 'hle'.
'hle' inserted inside 'attic' is 'ATHLETIC'.
(Other definitions for athletic that I've seen before include "Sporty, able-bodied" , "Wigan, for example" , "Strong and sporty" , "Powerful" , "Physically fit, strong and active" .)