Right bit of trouble with northern element (5)
I believe the answer is:
radon
'element' is the definition.
(radon is a kind of element)
'right bit of trouble with northern' is the wordplay.
'bit of' suggests taking the first letters.
'trouble' becomes 'ado' (I've seen this before).
'with' says to put letters next to each other.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
The initial letter of 'right' is 'r'.
'r'+'ado'+'n'='RADON'
(Other definitions for radon that I've seen before include "Radioactive gas, linked to granite" , "Colourless gas, atomic number 86" , "A radioactive gas, symbol Rn" , "Noble gas, Rn" , "Inert gas that occurs naturally" .)