Trials new English and Scottish flag (7)
I believe the answer is:
saltire
'scottish flag' is the definition.
(I've seen this before)
'trials new english' is the wordplay.
'new' indicates an anagram.
'english' becomes 'e' (abbreviation).
'trials' is an anagram of 'saltir'.
'saltir'+'e'='SALTIRE'
'and' acts as a link.
(Other definitions for saltire that I've seen before include "flag - 8's? [SAINT ANDREW]" , "The Scottish flag" , "Scottish cross" , "X-shaped cross" , "Heraldic cross" .)