Nearly nothing can be found at bottom of storeroom (5,2)
I believe the answer is:
close to
'nearly' is the definition.
(thesaurus)
'nothing can be found at bottom of storeroom' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'can be found at bottom of' says to put letters next to each other.
'storeroom' becomes 'closet'.
'o' put after 'closet' is 'CLOSE TO'.
(Other definitions for close to that I've seen before include "Nearly" , "'Nearby (5,2)'" , "near" .)