Shyness (7)
'shyness' is the definition.
This is all the clue.
(Other definitions for reserve that I've seen before include "One on bench" , "Keep back - book" , "Modesty- store" , "Hold back" , "man on bench?" .)
(Other definitions for modesty that I've seen before include "Humility; decency" , "Diffidence" , "Decorum, shyness" , "Unassumingness" , "Unassuming character" .)