Charity is oddly all amiss (4)
I believe the answer is:
alms
'charity' is the definition.
(alms is a kind of charity)
'oddly all amiss' is the wordplay.
'oddly' means one should take alternating letters (letters in the odd-numbered positions are used).
'all'+'amiss'='allamiss'
The alternate letters of 'allamiss' are 'ALMS'.
'is' acts as a link.
(Other definitions for alms that I've seen before include "Relief for the poor" , "handed over as charity" , "help" , "Charitable aid to poor" , "Charitable donations to the needy" .)