On policing, essentially Eastern girl bites tongue (6)
I believe the answer is:
gaelic
'bites tongue' is the definition.
'Gaelic' can be an answer for 'tongue' (Gaelic is an example). I am not sure about the 'bites' bit.
'on policing essentially eastern girl' is the wordplay.
'on' says to put letters next to each other.
'essentially' indicates the central letters.
'eastern girl' becomes 'gael' (I am not sure about the 'eastern' bit.).
The centre of 'policing' is 'ic'.
'ic' put after 'gael' is 'GAELIC'.
Can you help me to learn more?
(Other definitions for gaelic that I've seen before include "Characteristic of the Celts" , "tongue" , "Irish language or Celtic language of Scotland" , "The native language of Ireland" , "Language of the Celts" .)