Copy out letters from crest in bar (10)
I believe the answer is:
transcribe
'copy out' is the definition.
(thesaurus)
'from crest in bar' is the wordplay.
'from' is an anagram indicator (the anagram comes from the same letters).
'crest'+'in'+'bar'='crestinbar'
'crestinbar' is an anagram of 'TRANSCRIBE'.
'letters' acts as a link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for transcribe that I've seen before include "Copy into another form" , "write up" , "Copy out longhand" , "Take down" .)