Assumed authority of crew left in case of trouble (6)
I believe the answer is:
mantle
'assumed authority' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'crew left in case of trouble' is the wordplay.
'crew' becomes 'man' (I've seen this before).
'left' becomes 'L' (common abbreviation).
'in' indicates putting letters inside.
'case of trouble' becomes 'te' (I am not sure about this - if you are sure you should believe this answer much more).
'l' placed within 'te' is 'tle'.
'man'+'tle'='MANTLE'
'of' is the link.
Can you help me to learn more?
(Other definitions for mantle that I've seen before include "Lament in loose cloak" , "Cloak or loose outer garment" , "Gas lamp part; cloak" , "Robe or gas-lamp fitting" , "Loose outer garment or covering" .)