Month of unusual charm (5)
I believe the answer is:
march
'month' is the definition.
(March is an example)
'unusual charm' is the wordplay.
'unusual' indicates anagramming the letters.
'charm' with letters rearranged gives 'MARCH'.
'of' acts as a link.
(Other definitions for march that I've seen before include "Protest; month" , "Moving demonstration" , "make progress" , "Journey undertaken by army etc" , "Military walk; month" .)