Relevant language, close to legalese (7)
I believe the answer is:
germane
'relevant' is the definition.
(germane can mean relevant or pertinent)
'language close to legalese' is the wordplay.
'language' becomes 'german' (German is a language).
'close to' suggests the final letters (the 'close' to the word).
The final letter of 'legalese' is 'e'.
'german'+'e'='GERMANE'
(Other definitions for germane that I've seen before include "Material" , "Apposite" , "apt" , "Relevant to current topic" , "Relevant, to the point" .)