Part of speech in which nothing initially is ruled out (6)
I believe the answer is:
ration
'part' is the definition.
(ration is a kind of part)
'speech in which nothing initially is ruled out' is the wordplay.
I cannot really understand how this works, but
'nothing' could be 'o' (looks like zero - 0) and 'o' is located in the answer.
'in' is within the answer.
The remaining letters 'rat' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for ration that I've seen before include "Restricted share" , "Restrict the consumption of something" , "A fixed allowance in times of scarcity" , "Dole out portion due to shortage" , "Wartime allowance?" .)