Critic of a policy change in theory every so often (8)
I believe the answer is:
attacker
'critic' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'a policy change in theory every so often' is the wordplay.
'policy change' becomes 'tack' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' indicates putting letters inside.
'every so often' indicates alternate letters.
The alternate letters of 'theory' are 'ter'.
'tack' placed inside 'ter' is 'ttacker'.
'a'+'ttacker'='ATTACKER'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for attacker that I've seen before include "One charges" , "Person who assaults or acts violently towards" , "Assailant" , "Mugger" .)