Tolls fail to disturb armadas (9)
I believe the answer is:
flotillas
'armadas' is the definition.
Although both the answer and definition are plural nouns, I cannot see how they can define each other.
'tolls fail to disturb' is the wordplay.
'to disturb' is an anagram indicator (I've seen 'disturbed' mean this (the order of letters is disturbed)).
'tolls'+'fail'='tollsfail'
'tollsfail' anagrammed gives 'FLOTILLAS'.
Can you help me to learn more?
(Other definitions for flotillas that I've seen before include "vessels in groups" , "Small fleets" , "boats" .)