Rise of long-tail gnats aerially covering part of Britain (4,6)
I believe the answer is:
east anglia
'part of britain' is the definition.
'east anglia' can be an answer for 'part' (I have seen 'Part of UK' mean 'east anglia' so perhaps 'part' could also mean 'east anglia'). I'm not certain of the 'of britain' bit.
'rise of long-tail gnats aerially covering' is the wordplay.
'rise of' says the letters should be written backwards (in a down clue, letters go up).
'covering' says the answer is hidden in the clue.
'ailgnatsae' can be found hidden inside 'long tail gnats aerially'.
'ailgnatsae' back-to-front is 'EAST ANGLIA'.
Can you help me to learn more?
(Other definitions for east anglia that I've seen before include "part of England" , "Steal again (anag.)" , "Part of UK" , "Region of England" , "UK region" .)