Dressed like a constable but almost entirely ignorant (9)
I believe the answer is:
uniformed
'dressed' is the definition.
(uniforming is a kind of dressing)
'like a constable but almost entirely ignorant' is the wordplay.
I cannot quite see how this works, but
'like' could be 'uniform' (I've seen this before) and 'uniform' is located in the answer.
The remaining letters 'ed' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for uniformed that I've seen before include "Like most police" , "Wearing special clothes" .)